Naphthalanotherapy (NT) is a therapeutic procedure that uses mineral oil obtained from petroleum. The aim of this study was to investigate the influence of the duration of NT combined with an individually adjusted rehabilitation program (IARP) on pain, morning stiffness (MS), fatigue, and physical function in patients with psoriatic arthritis (PsA). A total of 29 consecutive patients with PsA were divided into two groups. Group 1 (n=17) participated in a two-week and Group 2 (n=12) in a three-week intervention program. Pain (using the Visual Analogue Scale - VAS), fatigue (VAS and Functional Assessment of Chronic Illness Therapy-Fatigue - FACIT-F), duration of MS (minutes), and physical function (Health Assessment Questionnaire - HAQ) were assessed before and after therapy. Statistical analysis was performed using SPSS version 20, with P<0.05. There was a significant improvement in VAS-pain, VAS-fatigue, MS, HAQ, and FACIT-F before vs after therapy: Group 1:5.88±1.62 vs 3.94±1.25, P=0.001; 6.59±1.73 vs 4.35±1.73, P=0.001; 35.47±31.64 vs 23.71±29.30, P=0.001; 1.43±0.78 vs 1.23±0.74, P=0.001; 25.88±10.89 vs 30.71±10.65, P=0.009; Group 2: 6.17±1.27 vs 3.92±1.44, P=0.001; 6.50±1.93 vs 3.75±1.71, P=0.001; 38.42±32.00 vs 21.25±17.31, P=0.006; 1.47±0.79 vs 0.93±0.54, P=0.008; 25.00±9.87 vs 36.83±7.20, P=0.001, respectively. Regarding the length of the therapy, significant difference was reached only in FACIT-F (P=0.009). Two-week and three-week NT combined with IARP are equally efficient in reduction of pain and MS, as well as in improving physical function in patients with PsA. The three-week program showed an additional effect on reducing fatigue assessed by the FACIT-F score.