Objective:To investigate genotypes and alleles’ distributions of inducible nitric oxide synthase (NOS2) gene (CCTTT)n polymorphism in Han nationality in the southwest of China

and make comparisons with different race or the same race in different areas.Methods:The (CCTTT)n polymorphisms of NOS2 gene were analyzed in a total of 205 southwestern Chinese healthy subjects by polymerase chain reaction (PCR)-8% denature polyacrylamide gel electrophoresis(PAGE)-silver staining and DNA sequencing.Results:(1)Nine alleles and thirty genotypes were identified.(2)(CCTTT) 9

(CCTTT) 10

(CCTTT) 12

(CCTTT) 13 alleles frequencies of NOS2 gene in Chinese Han population in southwestern area differed significantly from those in northern area.(3)(CCTTT) 9

(CCTTT) 10

(CCTTT) 11

(CCTTT) 15

(CCTTT) 16 alleles frequencies of NOS2 gene in Han population of the southwest of China differed significantly from those of Caucasians in England.Conclusion:The (CCTTT)n microsatellite polymorphisms of NOS2 gene are different not only among different ethnic populations but also within the same population of different areas

which may be of significance in the studies on relationship between genetics and disease.