A method has been developed to produce lipid emulsion particles for parenteral use as drug carriers. The technique uses a mixture of a triacylglycerol oil and purified egg yolk phosphatidylcholine (EPC) as the basic system and sonication under mild conditions to produce the emulsion. A large number of mild "biological" surfactants were tested for their ability to improve the dispersing and stability properties of the basic system. The results showed a preference for polysorbate 80, and a suitable combination of oil and emulsifiers was found to be castor oil:EPC:polysorbate 80 (1:0.4:0.12, weight ratios). Repeated preparation of this emulsion system in phosphate-buffered saline (PBS) gave particles with a mean diameter near 50 nm, in a reproducible way and with a low polydispersity. The stability of the emulsion was very good (> 3 months), both in PBS and in 2.5% glycerol. The method was also tested with two lipophilic anticancer drugs, which were solubilized in castor oil, with satisfactory results. The lipid emulsion particles described in this study also have a potential use as targetable carriers for site-specific drug delivery.