Sclerotium cepivorum is the etiologic agent of garlic "white rot". Knowledge of genetic variability of the fungus may help to design efficient strategies for its control. For this study, 47 isolates obtained from Aguascalientes, Guanajuato and Zacatecas as well as 7 reference strains were used. Morphological characterization was that established for this organism. PCR amplification of ribosomal 18S gene generated a DNA fragment of a size close to 2.2 Kb in all isolates and reference strains, as compared to that of 1.8 Kb amplified in control fungi. Variability was analyzed by Random Amplified Polymorphism Distance (RAPD). Isolates exhibited a similar gene pattern with an average dissimilitud of 9.4%. Some of the bands identified here can be useful as molecular markers in identification studies of this plant pathogen. Dendogram analysis of data revealed a tendency of isolates to group according to their geographic procedence.