Objective: While the relationship between psoriatic arthritis and skin findings is well-known in patients with psoriasis, the relationship between psoriatic arthritis and nail involvement is less known. In this study, it was aimed to examine the frequency of association between nail involvement and psoriatic arthritis in patients with psoriasis. Materials and Methods: Our study is a retrospective observational study. It was conducted with 250 regis tered patients who applied to the dermatology polyclinic and clinic of our university hospital. The follow-up forms of the patients were scanned retrospectively and the findings were recorded. Results: The average age of the 250 patients evaluated in this study was 39.62 ± 9.30, and 133 (53.2%) of them were women. The frequency of nail involvement in psoriasis patients was determined to be 36.8% (n=92) and the frequency of arthritis was determined to be 8.8% (n=22). Nail involvement was statisti cally significantly more common in those with arthritis, and nail involvement was present in all of those with arthritis (P < .001). Nail involvement was significantly more common in those with only arthralgia (P < .001). A significantly higher average of nail psoriasis severity index was found in those with both joint and nail involvement compared to those with only nail involvement (P < .001). There was no statistically significant difference in terms of psoriasis area severity index average (P=.235). Proximal and distal interphalangeal arthralgia and sacroiliac arthralgia were found significantly more frequently in those with nail involvement than in those without nail involvement (respectively P=.007 and P < .001). There was no statistically signifi cant relationship between nail involvement with the presence of arthritis and the clinical type (respectively P=.288 and P=.955). Conclusion: Joint involvement and nail involvement in patients with psoriasis are closely related, and we think that nail and joint involvement in psoriasis patients should be evaluated together.