Thefirngi growth on Spanish ham surfaces is involved in flavor development. However, there is a lack of information about the metabolism of these molds. Five mold strains belonging to the Penicillium genera, isolated from Spanish ham surface, were used to evaluate their lipolytic activity in a meat substratum having a similar composition to that existing on the sugace of this traditional Spanish product. The samples were held at diflerent temperatures (3, 8 and 12C) and relative humidities (15%,85% and 9%) during 30 days. The lipolytic activity of all mold strains was clearly affected by the time and temperature of incubation. P. camemberti strains have the highest acidity index (A.I.) among the molds tested. However, samples inoculated with P. chrysogenum showed the highest thiobarbituric acid index (TBA).