Relationships between plasma testosterone levels and selected parameters of lipid metabolism were studied in a group of young sterile males prior to, during, and after hormone therapy. Initial hypertriacylglycerolaemia and decreased concentrations of HDL cholesterol returned to normal values after 30 days of methyltestosterone administration. LDL cholesterol concentrations decreased significantly as did plasma apolipoprotein B levels. These changes persisted also one month after cessation of treatment. The results suggest that restoration of initially decreased testosterone levels in the studied group of sterile males is associated with the restoration of the lipid profile.