[en] Cholesterol synthesis in neoplastic tissues is typically measured in incubations of minced tissue or tissue slices with 10 mM concentrations of individual substrates. Carbon incorporation into cholesterol from [¹⁴C] labelled substrates by freshly isolated hepatoma cells was measured after one hour incubation with 10 mm single substrates. These observations were extended by measuring cholesterol synthesis supported by [¹⁴C] substrates in a media containing a mixture of substrates at physiological concentrations: 5.0 mM glucose, 1.3 mM D(-)-3-hydroxybutyrate, 0.5 mM acetoacetate, 0.3 mM acetate, 0.3 mM oleate, 0.3 mM palmitate, 0.65 mM glutamine, 1.4 mM lactate and 0.1 mM pyruvate in Eagle's modified essential medium. Under single substrate conditions, the ketone bodies contribute substantially to cholesterogenesis. Estimates of the quantitative contribution of each substrate to total cholesterol synthesis are reported