Objective To compare differences in clinical activity and remuneration between male and female rheumatologists and to evaluate associations between physician gender and practice sizes and patient volume, accounting for rheumatologists’ age, and calendar year effects. Methods We conducted a population-based study in Ontario, Canada between 2000-2015 identifying all rheumatologists practicing as full-time equivalents (FTE) or above and assessed differences in practice sizes (number of unique patients), practice volumes (number of patient visits), and remuneration (total fee-for-service billings) between male and female rheumatologists. Multivariable linear regression was used to evaluate the effects of gender on practice size and volume separately, accounting for age and year. Results The number of rheumatologists practicing at or above one FTE increased from 89 to 120 from 2000 to 2015, with the percentage of females increasing from 27.0% to 41.7%. Males had larger practice sizes and practice volumes. Remuneration was consistently higher for males (between $46,000-$102,000 annually). Our adjusted analyses estimated that in a given year, males saw a mean of 606 (95% CI 107-1105) more patients than females did, and had 1,059 (95% CI 345- 1773) more patient visits. Among males and females combined, there was a small but statistically significant reduction in mean annual number of patient visits, and middle-aged rheumatologists had greater practice sizes and volumes than their younger/older counterparts. Conclusion On average, female rheumatologists saw fewer patients and had fewer patient visits annually relative to males, resulting in lower earnings. Increasing feminization necessitates workforce planning to ensure that populations’ needs are met.