Females of Aegla strinatii (n  =  466) were sampled monthly (September 2003 to September 2005) by means of sieves and traps from Rio das Ostras (24°38′16.2″S; 48°24′05.2″W), at Jacupiranga State Park, South of São Paulo State, Brazil. The reproductive period was markedly seasonal (from May to September) encompassing the Austral late autumn through late winter. This is in accordance to the pattern of reproductive period variations in relation to the latitudinal climate variability verified in species of Aegla. The proportion of adult females exhibiting the ovigerous condition was higher in young/small specimens as compared to old/large ones, and suggests the occurrence of senescence in the latter group. Average size at the onset of functional maturity in females was estimated as 16.66 mm of carapace length (rostrum excluded). The number of eggs per ovigerous females ranged from 1 to 325. Eggs are slightly elliptical and average size varied according to embryonic stage. Mean (± standard deviation) carapace length of juveniles (n  =  118) was 1.50 ± 0.05mm (range: 1.40-1.65mm).