We examine biologists leaving science in 38 OECD countries in the past two decades. In a cohort-based and longitudinal fashion, we follow individuals over time, from their first publication (N = 86 178). We examine four disciplines: AGRI (agricultural, biological sciences), BIO (biochemistry, genetics, molecular biology), IMMU (immunology, microbiology), and NEURO (neuroscience). Our Kaplan–Meier survival analysis of BIO shows that 60% of women are still in science after 5 years, 40% after 10 years, and only 20% after 19 years. Women in BIO are 23.26% more likely than men to leave science after 10 years and 39.74% after 19 years. Gender differences increase consistently in later career stages. They are high, but comparing the 2000 and 2010 cohorts, have slightly decreased over time.