Examination of specimens collected for the international leather trade provided data on two species of large, heavy-bodied snakes: blood pythons (Python brongersmai) from northeastern Sumatra and short-tailed pythons (P. curtus) from northwestern Sumatra. Measurement and dissection of 2063 P. brongersmai and 181 P. curtus revealed broad interspecific similarities in morphology (size, shape, sexual dimorphism), food habits (feeding frequencies, dietary composition) and reproductive output (reproductive frequencies, egg sizes, and clutch sizes). Females of both species attain larger sizes than males, mature at larger sizes, and contain larger abdominal fatbodies. Python curtus is more heavy-bodied and longer-tailed than P. brongersmai, and more heavily infested with gut parasites. Both species feed almost exclusively on commensal rodents. Feeding rates increase with body size, and vary seasonally. Reproduction is highly seasonal. Adult females reproduce biennially, producing an average clutch of 12 to 16 large (mean = 83 to 90 g) eggs. The data also enable us to comment on the sustainability of the existing commercial trade, which is based mainly on adult males, and adult plus juvenile females. Anthropogenic habitat modification (especially, the establishment of oil-palm plantations) has increased the abundance of these taxa. Although neither species is likely to be extirpated by current levels of offtake, we need additional information to evaluate long-term sustainability of the commercial industry based on these snakes.