This study aimed to investigate the relationship of hand grip strength on upper extremity functionality, activities of daily living, and physical activity level in female patients with lymphedema who have undergone breast cancer surgery. A total of 15 female patients with a diagnosis of lymphedema associated with breast cancer treatment were included in the study. The presence and severity of lymphedema were determined by circumference measurement. A hand dynamometer was used to evaluate the hand grip strength. Disabilities of Arm, Shoulder and Hand Questionnaire (DASH); Milliken Activities of Daily Living Scale (MAS);and the long form of the International Physical Activity Questionnaire(IPAQ) were used to evaluate upper extremity functionality, daily living activity, and physical activity level, respectively. The mean age of the patients was 51±10.6 years. DASH score was significantly related with age (r:0.639; p:0,010). The relationship between the hand grip strength of the affected side and the hand grip strength of the unaffected side was statistically positively significant (r:0.756; p:0.001).It was determined that hand grip strength was related to the total MAS value and the DASH score (r:0.609;p:0.016 and r:-0.624; p:0.013, respectively). The relationship between postoperative lymphedema development time with affected side hand grip strength and total MAS score was statistically significant (r:0.574; p:0.025 and r:0.766; p:0.001, respectively). There were no correlations between IPAQ score and hand grip strength, DASH, and MAS values (p>0.05). Considering these results, we concluded that improving hand grip strength in the early period may increase upper extremity functionality and quality of life for these patients.