Objective. Fertility is reduced in women with rheumatoid arthritis (RA), even before diagnosis. This may be due to a diminished ovarian reserve. The current study examined serum levels of anti-Mullerian hormone (AMH), the most reliable endocrine marker for ovarian reserve, in early RA patients and the influence of disease activity and methotrexate (MTX) use on AMH concentrations. Methods. Serum AMH levels were measured in 72 women with recent-onset RA ages 18-42 years and compared to 509 healthy women. The association between AMH and rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP), erosions, C-reactive protein (CRP) level, disease activity (Disease Activity Score in 28 joints [DAS28]), and use of MTX was assessed. Results. At diagnosis, age-adjusted serum AMH levels did not differ significantly between patients and controls (P = 0.254). AMH levels were not related to the presence of RF (P = 0.487), anti-CCP (P = 0.686), or erosions (P = 0.350), and showed no significant correlation with CRP levels (r = -0.207, P = 0.083) or disease activity scores (DAS28; r = 0.007, P = 0.955). After 6 months of treatment, AMH levels in patients (n = 53) were lower than at the time of diagnosis (P < 0.001), but did not di Conclusion. AMH levels in women with early RA are comparable to those of healthy controls, indicating that the reduced fertility in this patient group is not caused by diminished ovarian reserve. AMH levels are not affected either by disease activity or by short-term MTX use.