Introduction. Psoriatic arthritis (PsA) is an inflammatory joint disease associated in up to one-third of patients with psoriasis. Studies performed on PsA showed the high burden of the disease, but it still has not been totally quantified due to variable course of the disease. The applicability of the existing clinical tools in the disease activity appreciation still needs to be approved. The objective of the study was the assessment of the disease activity level and the evaluation of reliability and applicability of disease activity measures in PsA. Materials and methods. A descriptive study of 46 PsA patients was performed. The disease activity indices for PsA were evaluated and compared. The level of the disease activity according to each index was assessed and applicability of these indices was appreciated. Results. The disease activity by Disease Activity Index for Psoriatic Arthritis (DAPSA) was appreciated as moderate in nearly half of the patients (47.8%), and according to Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) moderate disease activity was assessed in 56.5% cases. Minimal disease activity was encountered in only 8.69% of patients. Psoriasis Area and Severity Index (PASI) was estimated as moderate (mean 20.21 points). The data analysis of clinical tools showed that the most affected were pain and general condition, objectified by Visual Analogue Scale (VAS) and Patient Global Assessment (PGA). Conclusions. The DAPSA demonstrated the highest objectiveness and was best able to designate between different levels of disease activity. DAPSA together with Minimal Disease Activity index (MDA), were best related to patient's quality of life. Therefore, assessing the activity of the disease by MDA and DAPSA can be recommended for use in clinical practice.