Social and environmental scientists usually argue that political parties hold hostile positions towards GMOs, yet we are confronted with a lack of systematic comparative analyses in the West European context. Conducting a quantitative content analysis of 265 election manifestos in seven Western European countries from 1990 until 2020, we test this assumption and explore the salience of GMOs in election manifestos and the positions of political parties on this domain. Our findings reveal that GMOs are neither a particular salient nor ignored issue by political parties and that most party families do tend to reject GMOs. Mainstream parties are more likely to talk about GMOs and to take a critical stance during periods of high mobilization of anti-GMO movements. Additionally, we hypothesize that the presence of a Green party in the national party system may make a difference. The findings provide insights into mainstream parties’ behaviour on niche issues and information for the scientific community about how political parties may become less hostile towards GMOs.