A study was conducted to determine how universal cholesterol metabolism is and to determine if there was any relationship between cholesterol metabolism and sexual reproduction among species of Pythium [P. periplocum, P. prolatum, P. aphanidermatum, P. polytylum, P. splendens, P. dissotocum, P. sylvaticum, P. heterothallicum] and Phytophthora [P. megasperma, P. cactorum, P. parasitica]. Uptake of cholesterol by homothallic isolates which produced normal oospores under the conditions of the experiment varied between 41-85%. Production of polar metabolite varied 0.9-7.7% of the cholesterol taken up. Ester production among these isolates varied 1.9-18.4% of the cholesterol taken up. More isolates produce sizable quantities of ester than produce sizable quantities of polar metabolite, and there appears to be no correlation between polar metabolite production and ester production. There was no apparent relationship between sterol metabolism and reproduction. If a diffusable steroid hormone such as antheridiol was produced, its presence was masked by the other metabolites or products of sterol autoxidation prevalent under the cultural conditions used in this study.