This study aimed to survey the impact of smartphone overuse on upper extremity pain, anxiety, depression, and interpersonal relationships among college students. Subjects completed a structured questionnaire consisting of the Smartphone Addiction Inventory, the Musculoskeletal Symptom Checklist, the State-Trait Anxiety Inventory, the Beck Depression Inventory-II, and the Relationship Change Scale from May to June 2012. We analyzed the survey data from 525 responses, excluding unreturned or incomplete surveys. Data were analyzed using the x2 test and t-test to determine the differences in smartphone overuse and its impact on upper extremity pain, anxiety, depression, and interpersonal relationships between two groups: the overuse and normal use groups. Moreover, Pearson's correlation coefficient was used to examine the correlation between smartphone overuse and upper extremity pain, anxiety, depression, and interpersonal relationships. The results placed 62 people (11.8%) in the smartphone overuse group. The extent of smartphone overuse was more severe among female than male college students ,and longer time spent using smartphones per day was directly related to smartphone overuse. The smartphone overuse group evidenced higher shoulder pain than the normal use group did, but no differences were found in other sites of the upper extremities. State anxiety, trait anxiety, and depression were higher in the smartphone overuse group than in the normal use group. Subjects with a higher extent of smartphone overuse experienced increased state-anxiety, trait-anxiety, and depression. Moreover, subjects with higher state-anxiety, trait-anxiety, and depression scores were more likely to have poor interpersonal relationships. Therefore, early screening for smartphone overuse should be evaluated, because it can be useful in developing addiction prevention programs to improve posture, stress coping, positive mental health, and effective interpersonal relationships.■ keyword :|Smartphone Overuse|Upper Extremity Pain|Anxiety|Depression|Interpersonal Relationship|