Résumé : We investigated the vegetation composition of three inselbergs from continental Equatorial Guinea in relation to six environmental variables. The most influent factors on vegetation appeared to be soil depth, pH and the position relative to the upper or lower forest fringe. There was no effect of slope or aspect. Although the three inselbergs are very close to each other (100 to 500 m), they significantly differ in their vegetation (site effect). This effect could partly be explained by the insular property of inselberg vegetation surrounded by rainforest. The position of Afrotrilepis pilosa (W.C.Boeck) J.Raynal, the most characteristic species of West African inselberg grasslands, along the main ecological gradient is discussed.