The yeast Malassezia spp has an established etiological role in pityriasis versicolor, folliculitis, systemic infections and onychomycosis. Aim: To assess the presence of Malassezia spp in patients with seborrheic dermatitis (SD), to find a correlation between Malassezia spp count and the severity of the disease and to compare the prevalence of the different Malassezia species in SD patients and subjects without skin lesions. Patients and methods: Scrapings of the face from 81 patients with SD (69 males) and 79 subjects (54 males) without skin lesions were obtained for a direct microscope examination and yeast culture. Results: The yeast Malassezia was found in 76% of SD patients and in 82% of subjects without skin lesions. There was a positive correlation between the number of yeasts found on direct examination and the clinical severity of lesions in SD patients. Although this correlation was statistically significant (p=0.046), the degree of association (rho=0.22) was weak. Fifty Malassezia species were identified. M globosa was found in 67% of SD patients, followed by M furfur and M sympodialis, each present in 16.5% of the SD patients. In subjects without skin lesions, the most prevalent species were M globosa (77%), followed by M sympodialis (12%), M slooffiae (7%) and M furfur (4%). Conclusions: The presence of the yeast Malassezia is not associated with the presence of skin lesions (Rev Méd Chile 2003; 131: 1295-300)