1. Needle biopsy specimens of liver were obtained from six control subjects with histologically normal liver and 11 chronic alcoholics with fatty liver.
2. Micro- and macro-lipid droplet fractions were isolated by differential flotation. These fractions, together with the sedimenting membranes, were assayed for cholesterol, cholesteryl ester, phospholipid, free fatty acids and triglyceride.
3. Electron microscopy demonstrated marked differences in the range of lipid droplet sizes in the two fractions and biochemical analysis suggested that the microdroplet lipid corresponded to pre-very low density lipoprotein (VLDL) particles.
4. Studies on biopsies from patients with alcoholic fatty liver showed a 2–3-fold increase in triglyceride in both lipid droplet fractions but most of the accumulating triglyceride was sedimentable and membrane-bound.
5. Needle biopsy specimens from two patients with alcoholic fatty liver were fractionated with a vertical pocket re-orientating rotor. The principal organelles were separated and the subcellular distribution of triglyceride, phospholipid and free cholesterol determined. Triglyceride showed a bimodal distribution to a particulate fraction tentatively located to Golgi particles and to droplet-lipid remaining in the sample layer.