Recent studies introduced the novel concept of chemical lipolysis where phosphatidylcholine (PC), an active component of commercial preparations, plays a pivotal role. Other studies suggested that sodium deoxycholate (DOC), an excipient contained in medical preparations, could be the real active component performing an adipocytolytic action. We investigated the effects of PC and DOC on human primary adipocyte cultures and on human fresh adipose tissue. Human adipocytes isolated by Rodbell's method, were cultured onto type I collagen-coated glass coverslips, placed into 24-well tissue culture plates. Cells were incubated with or without DOC (5–7–9%), PC (5%) or DOC/PC mixture and observed under phase contrast microscope. After incubation, cells were stained with Oil Red-O and with acridine orange/ethidium bromide to observe necrotic cells with phase contrast microscope and fluorescent microscope, respectively. Histological specimens from adipose tissue biopsies were observed with phase contrast microscopy and with scanning electron microscopy. To investigate the lipid pattern variability in the different experimental conditions, culture medium obtained from the different treatments was subjected to lipid extraction and subsequently to thin layer chromatography (TLC). Microscopic observation of adipocytes showed that DOC treatment led to a detrimental morphological effect in a dose-dependent manner. PC treatment did not significantly affect adipocyte viability. On the contrary, results from experiments aimed to analyze the effects of PC/DOC combined treatment suggested a PC protective role against the DOC harmful effects on adipocytes. Results indicated that clinical effects, observed in local treatment with pharmaceutical preparation, could be due only to DOC, a detergent inducing nonspecific lysis of cell membranes following adipocyte necrosis. On the other hand, PC could likely be incorporated in the lipid bilayer, thus strongly reducing the disruptive DOC effects.