Although the middle and lower reaches of Changjiang River were consecutively stricken by severe flood in 1998 and 1999, the transmission of malaria was not frequent and prevalence of the disease was basically stable with no reports of outbreaks in the above areas, which was attributed to the intensification of malaria surveillance, prompt implementation of integrated measures including mosquito control and chemoprophylaxis, as well as the zoophilous trend of Anopheles sinensis , the vector in the stricken areas. According to the case reporting system established on the basis of professional institutions of 22 provinces, autonomous regions and municipalities (P/A/M), the number of malaria cases in the country totalled 29 039 in 1999,with lethal cases of 67. Based on pilot site surveillance and investigation of some localities, the actual number of malaria cases was estimated to be 250 000～300 000 in 1999. Hainan and Yunnan are still the major malarious provinces . The elongated borderline and increase in migratory population contributes to the difficulties in malaria control in Yunnan, consequently, the incidence of malaria was progressively upgrading in the last three years, the reported number of falciparum malaria cases and deaths was markedly increased in 1999 as compared with that in 1998,exhibiting a crucial status of prevalence in the province. In Hainan, circa 80% of malaria cases were infected via transmission by An. dirus away from villages, hence difficulties existed in malaria control; in areas affected by An. anthropophagus where a population of more than 100 million resided, relatively high incidence of malaria was noted, the prevalence was unstable, sometimes focal outbreaks occurred, and incidence of 20% was reported in a few villages and townships; in area where the only vector was An. sinensis , the prevalence was rather stable, the incidence of malaria was decreased to <0.1‰ in most places. A total of 26 797 people proved to be positive for malaria parasite in the process of blood examination on febrile cases of 7 816 182 man/time in area where lived 691 million population, covering 1 336 counties in 19 P/A/M, the mean parasite rate being 0.34%, however, the rate was as high as 2.09% in migratory people. Blood examination on targetted people including the inhabitants in the epidemic foci, children and migratory population for 362 512 man/time detected 1 781 malaria parasite carriers, with a mean parasite rate of 0.49%. Prevalence of falciparum malaria was still confined to 44 counties of Hainan and Yunnan provinces. Imported falciparum malaria cases were found in 114 counties of 16 P/A/M (areas not endemic for falciparum malaria in Hainan and Yunnan also included). Altogether 5 466 cases and 227 carriers of falciparum malaria (including mixed infection of Plasmodium vivax and Plasmodium falciparum ) were detected this year. Although the middle and lower reaches of Changjiang River were consecutively stricken by severe flood in 1998 and 1999, the transmission of malaria was not frequent and prevalence of the disease was basically stable with no reports of outbreaks in the above areas, which was attributed to the intensification of malaria surveillance, prompt implementation of integrated measures including mosquito control and chemoprophylaxis, as well as the zoophilous trend of Anopheles sinensis, the vector in the stricken areas. According to the case reporting system established on the basis of professional institutions of 22 provinces, autonomous regions and municipalities (P / A / M), the number of malaria cases in the country totalled 29 039 in 1999, with lethal cases of 67. Based on pilot site surveillance and investigation of some localities, the actual number of malaria cases was estimated to be 250 000 ~ 300 000 in 1999. Hainan and Yunnan are still the major malarious provinces. The elongated borderline and increase in migratory population contributes to the difficulties in malaria control in Yunnan, obtained, the incidence of malaria was progressively upgrading in the last three years, the reported number of falciparum malaria cases and deaths was markedly increased in 1999 as compared with that in 1998, exhibiting a crucial status of prevalence in the province. In Hainan, circa 80% of malaria cases were infected via transmission by An. Dirus away from villages, thus difficult existed in malaria control; in areas affected by An. Anthropophagus where a population of more than 100 million resided, relatively high incidence of malaria was noted, the prevalence was unstable, sometimes focal outbreaks occurred, and incidence of 20% was reported in a few villages and townships; in area where the only vector was An. sinensis, the prevalence was rather stable, the incidence of malaria was decreased to <0.1 ‰ in most places. A total of 26 797 people proved to be positive for malaria parasite in the process of blood examination on febrile cases of 7 816 182 man / time in area where lived 691 million population, covering 1 336 counties in 19 P / A / M, the mean parasite rate being 0.34% the rate was as high as 2.09% in migratory people. Blood examination on targetted people including the inhabitants in the epidemic foci, children and migratory population for 362 512 man / time detected 1 781 malaria parasite carriers, with a mean parasite rate of 0.49% . Prevalence of falciparum malaria was still confined to 44 counties of Hainan and Yunnan provinces. Imported falciparum malaria cases were found in 114 counties of 16 P / A / M (areas not endemic for falciparum malaria in Hainan and Yunnan also included). Altogether 5 466 cases and 227 carriers of falciparum malaria (including mixed infection of Plasmodium vivax and Plasmodium falciparum) were detected this year.