Abstract: This paper deals with the taxonomic revision of M.assamensis.After examining and analizing 32 specimens kept in China,we think M.a.coolidgei is a valid subspecies,and the assam macaques in westhern Yunnan probablly represent a new race,because the genetic deviation of mtDNA +in intraspecies of assam macaques between south Yunnan and west Yunnan is greater than that in interspecies between south Yunnan assam macaques and tibetan macaques (M.thibetana)(Zhang et al,1991).Through t-test on some cranial measurments,the difference between south and west Yunnan assam macaques in females is significant,and that between west and northwest Yunnan assam macaques in males is significant,too.As diagnoses distinguishing M.a.coolidgei from M.a.assamensis,the size of body is smaller in coolidgei (♂♂:HB 538-602 mm)than that in assamensis(♂♂:620-700 mm),the hair on the middle scapular-shoulder is shorter in coolidgei (35-75 mm,June-Dec.)than that in assamensis (85-110 mm,June-Sep.),and upper dorsal hair is not so clearly annulated (0-2 annuli) in coolidgei as that (3-4 annuli) in assamensis,and the hair,especially on hindpart,is greyer in coolidgei.