Despite increased enrolment of women and students from underrepresented racial/ethnic groups in doctoral programs, notable inequalities in academic careers persist. We investigate one potential source of these inequalities: publication rates during graduate school. Results, based on a sample of doctoral students in biological sciences across 53 institutions, indicate that both white women and students from underrepresented racial/ethnic groups (African American and Latinx) have lower publication rates than white men. Notably, these gaps grow over time and are not explained by background factors, socialization experiences, or family obligations. The same patterns persist for first-authored publications for African American and Latinx students, but not white women, suggesting potentially differential mechanisms of exclusion. Implications for research and practice are discussed.