Background: Neck-shoulder pain (NSP) and low back pain (LBP) increased among adolescents in the 1990s and the beginning of 2000. A potential risk factor for this increase is the use of information and communication technology. We studied how the use of computers, the Internet, and mobile phones, playing digital games and viewing television are related to NSP and LBP in adolescents. Methods: Mailed survey with nationally representative samples of 14-, 16-, and 18-year-old Finns in 2003 (n = 6003, response rate 68%). The outcome variables were weekly NSP and LBP. Results: NSP was perceived by 26% and LBP by 12%. When compared with non-users, the risk of NSP was 1.3 (adjusted odds ratios) when using computers > 2-3 h/day, and 1.8 when using 4-5 h/day; 2.5 when using computers >= 42 h/week, and 1.7 when using the Internet >= 42 h/week. Compared with non-users, the risk of LBP was 2.0 when using computers > 5 h/day, 1.7 when using >= 42 h/week, 1.8 when using the Internet >= 42 h/week, and 2.0 when playing digital games > 5 h/day. Times spent on digital gaming, viewing television, and using mobile phones were not associated with NSP, nor were use of mobile phones and viewing television with LBP after adjusting for confounding factors. Conclusions: Frequent computer-related activities are an independent risk factor for NSP and LBP. Daily use of computers exceeding 2-3 h seems to be a threshold for NSP and exceeding 5 h for LBP. Computer-related activities may explain the increase of NSP and LBP in the 1990s and the beginning of 2000.