113 psoriatic patients participated in the study. The patients were selected from the Dermatology and Venereology department at Alasad hospital in Lattakia city between 2012-2013 years. Mycological examination was carried out in all patients showing psoriatic nail changes .The aim of the study is to evaluate : the frequency of nail changes in psoriatic patients, the frequency of onychomychosis in patients with nail psoriasis and the factors that may have a role in the incidence of onychomcosis in patients with nail psoriasis. Nail changes were seen in (61.9%) of psoriatic patients (70 patients). Positive mycological cultures were obtained from 34 patients (48.6%). There was an increase of the incidence of onychomycosis in patients with high levels of NAPSI and long duration of psoriasis and nail psoriasis. There was a relationship between onychomycosis and the age of the patient. We found an increase of the incidence of onychomycosis among the patients who had a systemic therapy for psoriasis (methotrexate,cyclosporine) and the patients who had a history of contusion on nails. There was no relationship between onychomychosis and the gender of the patient. This study confirmed that onychomycosis may occur in patients with nail psoriasis