This study examines the existence of a gender earnings gap in the academic labour market with well-defined pay scales with panel data from the personnel records of a large university. We find that women earn approximately 10% less than men but that adjusting for different background characteristics and research performance decreases the gap to 2%. Our results suggest that the level of gender pay inequality is greater among older employees and lower for more productive employees. The results also imply that the gender gap is more pronounced in female-led departments than in male-led departments.