Objective: To investigate the correlation between total and bioavailable serum 25-OH vitamin D, ovarian reserve and ovarian response to controlled stimulation in egg donors.

Design: Retrospective study. Setting: University affiliated private IVF center. Intervention: Serum analysis of vitamin D, bioavailable vitamin D, antimullerian hormone (AMH), antral follicular count (AFC), reproductive outcome of oocytes recipients Main outcome measure: AMH, AFC, number of oocytes retrieved and number of mature oocytes, pregnancy and implantation rate of donated oocytes'recipients.

Inclusion Criteria:

• Caucasian race,
• between 18 and 34 years of age,
• all donors had normal menstrual cycles of 26-34 days,
• normal weight range (BMI 18- 25 Kg/m2),
• normal uterus and ovaries on transvaginal ultrasound (no signs of polycystic ovarian syndrome), and
• an antral follicle count (AFC) >10,
• normal karyotype

Exclusion Criteria:

• current or past exposure to radiation or hazardous chemical substances,
• history of drug use,
• family history of hereditary chromosomal diseases,
• sexually transmitted diseases

oocytes' donors who underwent ovarian stimulation cycles in our clinic from June 2013 to April 2014