The role of national parliaments in european integration is a topical issue in current political and academic debates. This article aims to contribute to these debates by formulating three hypotheses on the differences in parliamentary scrutiny between member states. It is hypothesised that due to differences in the structure of political systems, the british and dutch upper and lower house hold their respective governments to account in different ways. The hypotheses will be discussed in light of empirical findings on the eu regulation on the registration, evaluation, authorisation, and restriction of chemical substances (reach). The empirical evidence provides a mixed picture with regard to these claims.