Pulsed short wave diathermy (PSWD) has become a popular physiotherapy modality over the past thirty years for the treatment of knee osteoarthritis (OA). However, there is no agreement about appropriate dosages for this application. The aim of this study was to compare the outcomes of two methods of PSWD using different parameters. The study population consisted of 40 patients (14 males, 26 females) with knee OA diagnosed following the American College of Rheumatology criteria. The patients were randomly assigned to two groups: each of them was treated with one type of PSWD. After PSWD application, all patients received the same therapeutic ultrasound and progressive resistive exercise interventions. In both groups we observed similar significant differences between pre- and post-treatment measurements of quadriceps muscle strength, range of motion in active flexion, pain intensity, pain index of daily living activities, and time for walking over 25 meters distance. This study demonstrates that PSWDs with different parameters work as well.