This cross-sectional study evaluates the knowledge, attitudes, experiences, and behavior of final year medical students, PhD students, and supervisors at the School of Medicine of the University of Zagreb in relation to research misconduct, questionable research practices, and the research environment. The overall response rate was 36.4% (68%–100% for the paper survey and 8%–15% for the online surveys). The analysis reveals statistically significant differences in attitude scores between PhD students and supervisors, the latter having attitudes more in concordance with accepted norms. The results overall show a nonnegligible incidence of self-reported misconduct and questionable research practices, as well as some problematic attitudes towards misconduct and questionable research practices. The incidence of problematic authorship practices was particularly high. The research environment was evaluated as being mostly supportive of research integrity. [ABSTRACT FROM AUTHOR]