Introduction: This paper examines office staff’s knowledge and obedience of rules of computer workstation ergonomics and assesses how physical activity and obedience of ergonomic rules affect the level of pain intensity reported by office staff included in the study. Material and methods: The study group consisted of 136 persons (94 female and 42 male) aged between 20 and 46 (average 44,5±12,6 years) working on computer workstations. Results. Approximately 50% of the study group were spending their free time actively (72 persons, 52,9%). Preferred forms of activity were as follows: walking (72,1%), cycling (58,1%) and physical exercise (26,5%).Results: It was found that higher rates of physical activity significantly reduced the intensity of the pain resulting from computer work. On the contrary, a statistically significant number of people occasionally involved in physical activity more often suffered the following symptoms: pain in the shoulders (p=0,0224), hips (p=0,0036) and feet (p=0,0458), and tingling and sensory loss in lower extremities (p<0,0001). It was found that study group members regularly involved in physical activity less often suffered from the pain in the shoulders (22,9% vs 50,0%,), hips (14,3% vs 44,7%,) and feet (17,1% vs 31,6%), and tingling and sensory loss in lower extremities (2,9% vs 36,8%) when compared to the group with occasional physical activity. Statistically significant lower incidence of pain was observed in the study group members conforming to the rules of ergonomics at work as exemplified through the following symptoms: increased muscle tension in the shoulder areas (38,5% vs 61,8%, p=0,0303), pain in the upper parts of the spine (26,9% vs 50,9%, p=0,0274), eye pain, tearing and burning sensation (57,7% vs 80,0%, p=0,0170). Conclusions: 1. Only a small number of study group members complied with ergonomic rules at work. 2 It was observed that physical activity has a positive effect on pain reduction. 3. Adherence to ergonomic rules at work has a significant influence on reduction of pain intensity in examined groups.