Background: Fibrillin- 3 is a recently discovered hormone.However, there are no studies till now regarding the role of fibrillin-3 hormone on fertilization capacity in infertile pregnant and non-pregnant women. Objectives: The goals of this study are concentrated on the fertilization capacity parameters by examining the effect of in vivo concentration of fibrillin-3 hormone on the ovarians status at different menstrual cycle phases and to elucidate the correlation between the levels of this hormone with pregnant and non -pregnant women following Intrauterine insemination (IUI) outcome or through natural pregnancy. Methods: Sixty infertile couples were involved in this prospective study. The couples were divided according to the type of insemination and ovulation induction program into two groups Group(1): Thirty spouses were subjected to induced ovulation stimulation by using clomiphene citrate(CC) and recommended for natural coitus. Group(2): Thirty couples, the females were induced ovulation stimulation by CC, Gonal F-751U /ml and Fostimon 50IU/ml with IUI. Measurements of Fibrillin-3 with other reproductive hormones were done at different phases of menstrual cycle and for pregnant and non-pregnant women following natural coitus and IUI. Results: The mean of fibrillin-3 hormone level at day 2 of menstrual cycle was 3.7ng/ml (ranged from 3.50 to3.91) in the two groups. The mean of fibrillin-3 hormone at cycle day 13 was 6.6ng/ml( ranged from 5.83to 7.0). Whereas, The basal level of Fibrillin-3 at 14 days post insemination was 3.3ng/ml. The range is from 2.76,395 to 3.29 ng/ml. There was no significant difference in the mean of Fibrillin -3hormone between pregnant and non-pregnant women through the phases of menstrual cycle or between the two groups, but there is a significant value between fibrillin-3 post insemination and E2 day 2 and day 13 P<0.05. Conclusion: The present study concluded that Fibrillin -3 hormone has no role in pregnancy, but it may have a main relationship with estrogens reaction in folliculogenesis, oocyte maturation and follicular contents. Therefore, this hormone may be one of the new hormones that interfere with fertilization capacity.