Since 1 July 1977 all Swedish children aged 0-14 years with newly diagnosed Type 1 diabetes have been recorded on a central register. Out of 3228 patients registered up to 31 December 1985, 10 children (seven boys) had died during this time period. The overall mortality was 0.75 per 1000 patient-years. When compared with the general population the standardized mortality ratio (SMR) for both sexes was 2.09 (95% confidence limits 1.14-3.83). When analysed separately for sex, the higher mortality remained significant for males only (SMR = 2.61, 1.28-5.32). Five deaths were most probably due to diabetes and the remaining five were due to accidents, other diseases and, in one case, not identifiable with certainty. In comparison with previous studies there was a very low mortality in young-onset diabetic patients. However, short-term mortality is still significantly raised even in a country with a good economic and educational patient status and easy access to free hospital care.