Plasma and biliary lipids were assessed in four strains of Syrian hamsters [Charles River Lakeview, (CHR), Biobreeder F1B (BIO), Harlan Sprague-Dawley (HAR) and Sasco (SAS)] fed a cholesterol-free diet. 2. Plasma cholesterol differed with SAS > CHR > HAR > BIO. 3. BIO Hamsters had the lowest HDL and highest VLDL + LDL/HDL ratio, but their biliary secretion of bile acids, phospholipids and cholesterol was 50% lower than other hamsters. 4. Chenodeoxycholate was highest in CHR and the cholate:cheno ratio depressed in CHR hamsters. 5. CHR hamsters had the highest lithogenic index and cholesterol-saturated bile.