INTRODUCTION: Osteoarthritis is a progressive joint disease that affects one or more joints, leading to restricted movement, pain, and eventual disability. Despite the availability of various treatments and supportive care, managing osteoarthritis symptoms remains challenging. This study aimed to evaluate the effect of Hydroalcoholic olive leaf extract on pain reduction and daily functioning in elderly patients with knee osteoarthritis. METHOD: A randomized, controlled, factorial clinical trial was conducted in 2022-2023 with 100 elderly participants suffering from knee osteoarthritis. Participants were selected through consecutive sampling and randomly assigned to four groups using block-stratified randomization. In addition to routine treatment, participants in group I received topical olive leaf extract ointment, Group II received oral olive leaf extract capsules, and Group III received a combination of both treatments. The intervention was administered three times daily for eight weeks. The control group did not receive any olive leaf extract-based interventions. Pain intensity was assessed using a visual analog scale, and daily functioning and joint stiffness were measured using the Western Ontario and McMaster Universities Osteoarthritis Index questionnaire. Data were analyzed using SPSS software. RESULTS: The intervention groups showed significantly more significant reductions in mean pain scores than the control group (p <
0.05). The combination of oral capsules and topical ointment among the intervention groups demonstrated the most pronounced pain reduction. The mean score for daily functioning improved significantly over time in all groups (p = 0.007). A decrease of 1.19 units per time increment was observed in the group using the ointment, while the oral capsule group showed a decrease of 0.89 units, both statistically significant (p = 0.006). CONCLUSION: Hydroalcoholic olive leaf extract effectively reduces pain and improves physical functioning in elderly patients with knee osteoarthritis, offering a promising complementary treatment option for managing osteoarthritis symptoms.