The relationship between tumour growth, insulin status, blood lipids and adipose linoleic acid (LA, reflecting long-term LA intake) was studied in 19 Jewish women suffering from early and advanced stages (ES and AS) of ovarian and endometrial tumours. Blood insulin in patients with ES tumours was four times higher than the control value in cancer-free subjects, but fell to normal levels at AS and after ES surgery (PES). Tumours and abdominal adipose tissue (AAT) had 4-6 and 1.4-1.7 times as much insulin as non-cancerous control organs. Serum total cholesterol (CHOL) and LDL-cholesterol were high at ES, dropped below normal at AS, but normalised at PES, while HDL-cholesterol increased after ES surgery. Linoleic acid in subcutaneous adipose tissue (SAT) was high in controls (26.4 + 1.5% of total fatty acids), but lower in cancer patients (20.5 + 3.7%, P < 0.05), while palmitic acid showed the opposite change. The results suggest mobilisation of glucose, cholesterol and linoleic acid for the supply of energy and structural lipids to rapidly multiplying tumour cells and possibly for prostaglandin synthesis. They also raise the question of whether the high linoleic acid intake by the Jewish population in Israel predisposes individuals to tumour development.