Sexual maturity and breeding behaviour were studied in the freshwater crab,Barytelphusa guerini from April 1976 to March 1977. Animals attain sexual maturity at a carapace width of about 45 mm. The breeding period is from May to August with the peak activity during June and July. The post-reproductive and quiescent period is from September to December and the preparatory period for reproductivity extends from January to April. Adult animals with a carapace width of 45-60mm are reproductively more active while the activity declines in older animals. The animals show annual reproductive cycle and take part in reproduction twice during the life span, more so during the second year and less in the third year.