Objective To summarize the clinical and pathological findings of Alport syndrome (AS), detect the distribution of type Ⅳ collagen within basement membrane of patients with AS and evaluate the diagnostic value of indirect immunofluorescence (iIF) study of type Ⅳ collagen in AS.Methods Fourteen patients belonging to 12 families were collected from January 1990 to June 1996. The clinical examinations include biochemical examination, audiometry and ocular examination. IIF technique was used to detect the location of chains of type Ⅳ collagen in 6 renal and 5 skin specimens from 8 Alport patients.Results Among fourteen patients, 11 were male and 3 female (mean age 29.4 years). Microscopic hematuria was found in 13 patients, and recurrent gross hematuria in 7. All had proteinuria. Three patients presented nephrotic syndrome. Slowly progressive renal failure occured in 10 of 11 males (11-39 years) and 1 female (40 years). Sensorineural deafness was observed in 9 patients particularly high frequency sound. Anterior lenticonus were presented in 2. Five families transmitted as X-linked dominant (XD) trait and 3 autosomal dominant, 3 autosomal reccessive inheritance. In 7 renal biopsies, the findings by light microscopy mostly revealed focal and segmental sclerosis glomerulonephritis (4/7). The results of IF were negative in 4. Ultrastructural studies showed variable thicking, thinning of glomerular basement membrane (GBM) in 7 specimens with lamellation and basket wearing of GBM in 1. Using the iIF technique, the α 3, 4, 5 (Ⅳ) chains were observed to be absent within both GBM and EBM of 4 male XD-AS patients. Six patients were treated with hemodialysis, 2/6 with transplantation.Conclusion Alport syndrome (AS) is a heterogeneous hereditary disease characterized by progressive hematuric nephritis with or without sensorineural hearing loss and ocular defects. Ultrastructural alterations of GBM are helpful to the diagnosis of AS. IIF study suggests that type Ⅳ collagen in basement membrane of AS was abnormal and iIF study of type Ⅳ collagen chains distribution is useful for confirming the diagnosis of AS.