Two lines of M. incognita virulent to tomato cultivar carrying the Mi gene were selected from avirulent single egg-mass populations. Each line was obtained from a single juvenile belonging to two wild avirulent populations, one coming from France, the other from the Ivory Coast. For each population, two lines were established one maintained on the susceptible cv. Saint-Pierre and the other on resistant cv. Piersol at 20-25°C. Females of the two virulent lines were compared for their soluble proteins to each other and to their non-virulent homologous parent. Analyses were made on females. Some differences appeared between the females of the two lines of different geographical origin using two-dimensional gel electrophoresis (2-DGE) and a sensitive silver stain. Approximately 400 spots were resolved but due to technical difficulties of the technique, only a small number of them could be considered in comparing the virulent and avirulent lines. Small differences could be observed between the two lines of each population of different geographical origins and only one spot enabled the homologous virulent lines to be distinguished.