The purpose of this study was to compare the effectiveness of iontophoresis and phonophoresis methods using 5 % ibuprofen in patients with knee osteoarthritis. Forty patients (25 females, 15 males) with knee osteoarthritis were included in the study. The subjects were randomly assigned to iontophoresis and phonophoresis groups. The iontophoresis group (n=20) consisted 12 females and 8 males (mean age: 53.3±6.1, range: 41-65 years) while the phonophoresis group (n=20) consisted 13 females and 7 males (mean age: 54.9±6.7, range: 40–65 years). The iontophoresis group received the 5% ibuprofen iontophoresis + hot pack + exercise therapy. Phonophoresis group was applied 5% ibuprofen phonophoresis + hot pack + exercise. Evaluation criteria were 15 meters walking time, rest and walking pain, daily living activities such as kneeling, going up and down stairs and the Sickness Impact Profile (SIP) scores, and they were evaluated before and after therapy. After treatment in the both groups, there were statistically significant improvements in all parameters (p<0.01, p<0.001). In comparison of two groups, it were found statistically more significant improvements in 15 meters walking time in iontophoresis group (p<0.01) and in rest pain in phonophoresis group (p<0.05); there was no significant difference in the other parameters (p>0.05). In conclusion, both therapeutic modalities were found to be effective in patients with knee osteoarthritis, and no significant difference in the improvement rate was detected between the groups. Our study indicated that the iontophoresis and phonophoresis of ibuprofen can be used as alternative electrotherapy methods in the treatment of patients with knee osteoarthritis.