Introduction:The Intermittent and Constant Osteoarthritis Pain Scale (ICOAP) was developed in focus groups study to evaluate the severity of the pain among knee/hip osteoarthritis patients and its impact on the quality of life. Furthermore, it is the only scale that can evaluate the constant and intermittent pain that could present in osteoarthritis patients. It can also be used for following the progression of the disease, the treatment responsiveness, and the need to joint replacement. Objectives: This study aimed to translate and adapt ICOAP questionnaire into the Arabic language, and evaluate the validity and reliability of this scale in participants with knee/hip osteoarthritis Methods: This questionnaire was translated based on Manufacturers Alliance for Productivity and Innovation (MAPI) protocol. Test-retest reliability was calculated using Intraclass Correlation Coefficient (ICC). Then, Cronbach’s alpha was used to assess the internal consistency of ICOAP. Lastly, criterion validity was evaluated against Knee injury and Osteoarthritis Outcome Score (KOOS). Results: A total number of 90 participants were included in this study, out of which 29 participants were reevaluated for the reliability. The ICC of the knee ICOAP was 0.841, 0.923 and 0.911 for the total knee pain, constant and intermittent knee pain, respectively. Moreover, the ICC of the Hip ICOAP was 0.969, 0.98 and 0.95 for the total hip pain, constant and intermittent hip pain. Cronbach’s alpha was 0.88, 0.93 and 0.94 for the total score, Intermittent and constant knee pain respectively. Additionally, Cronbach’s alpha of hip ICOAP was 0.977, 0.963 and 0.985 for the total score, intermittent and constant hip pain, respectively. The criterion validity was r = 0, 24 (P< 0.05), it reveals that there is a correlation between the total score of ICOAP and KOOS pain subscale.