The associations between temperature and daily mortality was studied among the citizens of Oslo, Norway, 1990-1995. Data on daily mortality were linked with daily temperatures, relative humidity, wind velocity and air pollution. At temperatures below 10 degrees C, a 1 degrees C fall in the last 7 days average temperature increased the daily mortality from all diseases by 1.4%, respiratory diseases 2.1%, and cardiovascular diseases 1.7%. Above 10 degrees C, there was no statistically significant increase in daily mortality, except for respiratory mortality, which increased by 4.7% per 1 degrees C increase in the last 7 days average temperature. Daily mortality in Oslo increases with temperatures falling below 10 degrees C. The increase starts at lower temperatures than shown in warmer regions of the world, but at higher temperatures than in regions with even colder climates. As well insulated and heated dwellings are standard in Norway today, more adequate clothing during outdoor visits is probably the most important preventive measure for temperature related mortality.