Objective: To evaluate the effect of kinetotherapy rehabilitation program on knee osteoarthritis in patients with different pain levels. Methods: We performed a cross-sectional study with patients with moderate knee osteoarthritis from a University Rehabilitation Center. All patients underwent a standard kinetotherapy program. Pain intensity, knee range of motion were evaluated using the visual analogue scale, universal goniometer, and Knee Injury and Osteoarthritis Outcome Score (KOOS) with five domains. Patients were classified into three groups according to pain intensity: mild,moderate, and severe pain groups. The evaluation was performed before (T0) and after a 1-week rehabilitation program (T1). Results: In the study were included 82 patients (19 men and 63 women) the mean age 61.8±9.2 y and, the disease duration was 5.96±4.2 y. Group 1 mild pain VAS (5-39mm) 10 patients, group 2 with VAS 40-69mm -39 patients, and group 3 with severe pain -33 patients. All groups showed significant differences in pain intensity, knee range of motion, and knee function. The VAS score change in mild (p=0.01) and moderate pain (p=0.002) groups and were significantly greater than those in severe pain group (p=0.43). The pre-intervention KOOS score of the mild pain group was higher than those of the groups 2 and 3 (p=0.05). There were significant improvements in the KOOS scores after 1-week rehabilitation program. At T1 KOOS score of the Group 1 was significantly higher than those of the moderate and severe pain groups (p=0.001), and that of the Group 2 group exceeded significantly group 3 (p=0.010). Conclusion: Pain intensity is one of the most important factors that are responsible for the improvement of knee osteoarthritis. The intensity of the pain should be taken into consideration during individual selection of the kinetotherapy program in knee osteoarthritis patients.