Dry eye is a very common condition among many women. Women are said to be twice likely to have dry eyes than men. Research suggests that dry eyes may be related to women’s monthly cyclical changes in hormone levels, particularly estrogen levels. (Fresina and Campos, 2007). The menstrual cycle has been reported to affect many physiological processes. In addition to the effects of the menstrual cycle on the cardiovascular and nervous systems, it has also been reported to affect such ocular parameters like intraocular pressure, visual acuity, tear volume and tear stability (Tarlipinar et al, 2001). In Nigeria, there is a dearth of literature on effects of the menstrual cycle on tear volume and tear stability. This study was a cross sectional one to investigate the changes in tear volume (TV) and tear stability (TS) during the different phases of the menstrual cycle in Nigerian women. 100 healthy women aged 20 to 35years with regular cycles of 26 to 29 days were recruited for this study after informed consent was obtained from them. They were screened for systemic and ocular diseases. Exclusion criteria included irregular menstrual cycle, use of oral contraceptive pills, history of hypertension, cardiovascular abnormalities, diabetes mellitus and any ocular infections that could affect tear volume or stability. They were examined for changes in tear volume and tear stability during the follicular, ovulation and luteal phases. Ophthalmoscopy was done to rule out any posterior segment disease. Schirmer’s test, which measures tear volume and the noninvasive tear break up time (NTBUT) which measures tear stability were carried out. (Schaumberg et al, 2001). Values are in means ± S.E.M, compared by ANOVA and student t test. Tear volume across the phases of menstrual cycle was statistically significant, p < 0.0001- Follicular 24.76±1.26, Ovulation 17.54±1.33, Luteal 21.14±1.50 (n=100). Reduction in TV (follicular vs ovulation was significant, p<0.05 and increase in TV (ovulation vs luteal was also significant, p<0.05.) However the difference in tear volume between the follicular phase and the luteal phase was not significant (p>0.05). Increase in tear stability during the menstrual cycle was also statistically significant, p<0.05. Follicular 13.70±1.10, Ovulation 16.32±1.42, Luteal 18.44±1.53 (n=100). Hormonal variation during the different phases of the menstrual cycle influence tear volume and tear stability in healthy young women of reproductive age. These changes may be clinically significant particularly in contact lens wearers where fluctuations in ocular parameter may alter the contact lens fit leading to a possible change in comfort and reduced visual acuity. Keywords: Tears, menstrual cycle, follicular, ovulation, luteal.