Introduction:
Unexplained infertility refers to the absence of a definable cause for a couple’s failure to achieve pregnancy. Reproductive aging plays a role in pathogenesis of unexplained infertility. We investigated the results of ovarian reserve tests in unexplained infertility.

Material and methods:
The patients were divided into two groups: unexplained infertility (n = 148) and male factor infertility (n = 112). Follicle-stimulating hormone, estradiol, inhibin b levels and anti-Müllerian hormone levels were evaluated. Antral follicle count and ovarian volume measurements were performed.

Results:
The demographic variables were comparable. Follicle-stimulating hormone levels were higher in the unexplained infertility group than the male factor infertility group, although this difference did not reach statistical significance (p = 0.071). Estradiol levels, inhibin b concentrations and ovarian volume showed no difference between groups. However, antral follicle count was significantly lower in the unexplained infertility group than the male factor infertility group (p = 0.023). The median anti-Müllerian hormone concentrations were significantly lower in the unexplained infertility group 1.42 (0.4–6.2) than in the male factor infertility group (2.04 (0.64–8.2); p = 0.001).

Conclusions:
Although anti-Müllerian hormone values and antral follicle count were higher than the low thresholds, a statistically significant decline of ovarian reserve in the unexplained infertility group was found in the present study. This might be an undiagnosed reason for unexplained infertility.