In November 2005, 55.7 percent of 2 million Swiss voters approved a 5-year moratorium (ban) on the commercial cultivation of genetically modified (GM) plants within Switzerland. The present study examines how individual voting decisions were determined by (i) socioeconomic characteristics, (ii) political preference/ideology and (iii) agreement with a series of arguments in favour and against the use of GM plants in Swiss agriculture. The analysis is based on the data of the regular voter survey undertaken after national-level voting decisions in Switzerland. Among the socioeconomic characteristics, only the age group was clearly significant with individuals above 65 years less opposed to crop biotechnology. Several political preference/ideology variables were significant determinants of the vote, most notably the preferences about the role of the state in the economy. Perceived consequences of the use of GM plants for health, natural diversity of plants and animals were also strongly and significantly associated with approving and disapproving voter groups. The disapproving votes were not motivated by perceived benefits of GM-food production but mainly by perceived interests of Swiss science and industry. Our findings suggest that current concerns about the use of genetically engineered plants in agriculture may not automatically decrease with higher levels of education/knowledge and generational change. Furthermore, the analysis of the voter motives suggests that the public support for GM-free agricultural production would be even larger in other countries, where industrial interests in crop biotechnology are less pronounced.