This study utilized external loggers to measure computer input activities of 18 undergraduate online gamers for 10 consecutive days. Questionnaire survey was conducted to collect musculoskeletal complaints in participants’ upper limb right after data collection period. Collected data were compared with those of computer document processors and CAD designers collected in a pervious study. Averages daily operating period, number of keystroke and mouse click, typing and clicking speed were derived from collected data. Experimental results show online gamers have an average operation period of 7.67 hr/day. Their have significantly higher keyboard activities(2.74