Abstract: Methods and kits are provided for assessing the ovarian reserve and predicting the ovarian response to fertility treatments in a female subject. The serum levels of MIS are shown to be positively correlated with the production and retrieval of mature oocytes and serve as prognostic indicators for the female response to fertility treatment. The MIS levels can be monitored prior to and during fertility treatment and are useful to adjust the timing and dosage of treatments in order to produce optimal outcome in individual patients, to avoid ovarian hyperstimulation, or to indicate cancellation of an unsuccessful treatment. MIS can also be administered to women to stimulate follicle development and to prevent depletion of ovarian reserve.