Gender differences in item nonresponse are well-documented in high-stakes achievement tests, where female students are shown to omit more items than male students. These gender differences in item nonresponse are often linked to differential risk-taking strategies, with females being risk-averse and unwilling to guess on an item, even if it could gain them credits. In low-stakes settings, similar trends should not apply, as the students carry no consequence for their performance. Instead, test-taking motivation is argued to be the pivoting factor, with female students seen as more motivated and omitting fewer items than male students. In contrast to the high- and low-stakes achievement tests, less is known about gender differences in item nonresponse in student background questionnaires. Using cross-classified mixed effects models, we examined gender differences in item nonresponse on the Programme for International Student Assessment (PISA) 2018 student questionnaire across 80 countries and 71 scales. On average, the odds of male students omitting a questionnaire item were double the odds of female students, consistent with the expected trend in the low-stakes setting. However, we show that gender differences in item nonresponse are not merely a function of the stakes involved for individual students but a more complex phenomenon that is context-dependent and not necessarily stable across countries, scales' formats, and contents. We argue that examining differences in item nonresponse patterns could serve as a source of additional information about the students' test-taking behaviour and the quality of the questionnaire.