Stable preparations of microscopic particles were obtained from long-chain fatty acids by mechanical agitation of evaporated films in presence of buffer solutions. Oleic and linoleic acids were used. Studies of osmotic swelling and shrinking of the particles indicated that they are enclosed by semipermeable membranes. The particles, which were named ufasomes, are also capable of entrapping glucose in spaces inaccessible to enzymes. It was concluded that the ufasomes closely resemble phospholipid liposomes in their structure and properties.