The nuclear accident in Fukushima and the subsequent discussions about nuclear power influenced public acceptance of this technology. The aim of the present study was to examine why after the Fukushima accident some people converted from supporting nuclear power to opposing it or became undecided. Data from a longitudinal telephone survey with two measurement points were used. The first survey was conducted about 15 months before the accident in Fukushima and the second survey was conducted about 20 months after. The sample consisted of 561 respondents from the German- and French-speaking regions of Switzerland. Results suggest that changes in benefits perception were mainly. responsible for people's changes in attitude toward nuclear power. People perceived somewhat more risks related to nuclear power after the accident in Fukushima. This change in risk perception did not explain the attitudinal changes of proponents into opponents of nuclear power, however. (C) 2014 Elsevier Ltd. All rights reserved.