Hydroxylammonium nitrate(HAN) is a major constituent in a class of liquid monopropellants and is extensively used in nuclear industry and space propulsion.Previous toxicological studies have focused on oral,inhalation and dermal routes of exposure to HAN-based propellant blends.In this study,acute and subchronic toxicity of HAN in Wistar rats by intraperitoneal injections were evaluated.In this acute study,doses of HAN at 115,125,135,147,160 or 174 mg/kg were administered.No adverse effects were observed during a 14-day period and at gross histopathological examination.In the subchronic study,HAN at 7,14 or 28 mg/kg were administered for 13 weeks.The treatment with HAN caused significant changes in the weight of spleen,in the level of hematological parameters,total bilirubin,direct bilirubin,uric acid and carbondioxidecombining power and histopathological damages of the lung,liver,spleen and kidney.Overall,the study suggests that 13-week HAN treatment caused abnormal hematological changes and tissue lesions,and the risk of toxicity to mammals is not negligible. Hydroxylammonium nitrate (HAN) is a major constituent in a class of liquid monopropellants and is extensively used in nuclear industry and space propulsion. Previousvious toxicological studies have focused on oral, inhalation and dermal routes of exposure to HAN-based propellant blends. In this study , acute and subchronic toxicity of HAN in Wistar rats by intraperitoneal injections of like as.In this acute study, doses of HAN at 115, 125, 135, 147, 160 or 174 mg / kg were administered. Non-adverse effects were observed during a 14-day period and at gross histopathological examination .In the subchronic study, HAN at 7, 14 or 28 mg / kg were administered for 13 weeks. The treatment with HAN caused significant changes in the weight of spleen, in the level of hematological parameters, total bilirubin, direct bilirubin, uric acid and carbondioxidecombining power and histopathological damages of the lung, liver, spleen and kidney. Overall, the study suggests that that 13-week HAN treatment caused abnormal hematological chan ges and tissue lesions, and the risk of toxicity to mammals is not negligible.