Background: The paper aimed to assess the gait pattern in children and adolescents with juvenile idiopathic arthritis (JIA) treated at the rehabilitation center and to assess changes in this pattern after the end of treatment and 9 months later. Material and method: 50 children with JIA were enrolled into the study. 35 healthy volunteers were enrolled into the study for a comparison. Spatiotemporal and kinematic gait parameters were obtained using a movement analysis system. The Gait Deviation Index (GDI) was calculated. The assessment was performed three times: on the day of admission to the rehabilitation center, after the end of a 4-week treatment period and 9 months later. Results: With regard to the majority of spatiotemporal and kinematic parameters, differences in their distribution were highly statistically significant between the study group and the control group (p<0.001). In two subsequent tests differences were less significant when compared to the control group (p<0.01). In the study group ranges of motion in the sagittal plane in the hip (p<0.01), knee (p<0.001) and ankle joints (p<0.01) increased significantly between tests 1 and 2, and 1 and 3. A significantly lower value of GDI was observed in the study group (right limb; p=0.036). Conclusions: The gait pattern of children with JIA is significantly different from the one observed in healthy children. A rehabilitation program significantly improved gait in children with JIA, but differences compared to healthy children were still observed, and it indicates that the abnormal gait pattern became permanent in this group of subjects.