Genetic diversity and inter- and intraspecific differentiation are evaluated in 10 populations of four different species of the soil-dwelling genus Orchesella (Collembola, Entomobryidae). The degree of genetic variability is consistent with that observed in other insects and soil organisms. Values of genetic distance are very high and suggest that the species differentiated a long time ago. Two different procedures are used to estimate the rate of gene flow among six populations of O. villosa, but they give contradictory results: this species seems to be subdivided into two groups of populations (inland and coastal), which might represent two subspecies.