BACKGROUND: Occurrence rates of specific features of psoriatic nails, as well as the influence of variable clinical parameters on nail involvement in psoriasis, are not determined.OBJECTIVE: To evaluate the frequency and characteristics of nail involvement in patients with psoriasis and determine the relationship between nail psoriasis and clinical parameters (age, gender, family history, clinical type, age of onset, duration, joint involvement).METHODS: 228 psoriatic patients, who had not received any systematic or topical antipsoriatic treatment for at least a year, were consecutively selected to participate in this cross-sectional study.RESULTS: 66.7% of patients had nail psoriasis. A logistic regression model showed that none of the clinical covariates were statistically significant in predicting nail psoriasis.CONCLUSION: The majority of psoriatic patients presented nail psoriasis. The most common feature was oil drop. There was a difference in the prevalence of each feature between fingernails and toenails. In correlation with clinical parameters, nail psoriasis evolves independently.