Two weeks after the Chernobyl disaster 26 April 1986 a representative sample of 840 persons from the whole of Sweden were interviewed and compared with 216 persons from a high risk area for nuclear fallout. Probably due to a very unclear official information during the two first weeks after the accident confidence in information was lower in the high risk area. People in that area had to a higher degree changed their habits compared with the whole of Sweden. They were also more keen on shutting down the nuclear power program. There were significant differences between age groups and sexes concerning variables of information, reaction and acting for Sweden as a whole. By help of a threat index it was possible to record differences in variables of perception and experience. Interviewees with previous mental health problems developed more depressive reactions, but were less concerned of radiation injuries to themselves. Nine patterns of reaction were found by help of latent profile analysis.