Background: Infertility is defined as the inability to conceive after at least one year of unprotected intercourse. It is a complex disorder with significant medical, psychosocial, and economic problems. In about one third of couples are infertile. Approximately 167 million married women aged 15-49 years in developing countries were infertility. The present study aimed to determine the most common causes of female infertility in patients who visiting the National Ayuvedic Teaching Hospital, Borella, Sri Lanka. Methods: In this study 635 infertile (primary and secondary) women were selected to determine the causes of infertility. The subjects were selected from the gynecology clinic, between the periods of February 2015 to March 2016. The data were gathered using a questionnaire; and after that proper statistical method was applied to analyze the data. Results: From the results age between 28-37 years (37.16%) are more prevalent to infertility and the causes of infertility are mainly due to anovulatory cycle (31.18%) and menstrual irregularities (19.21%). BMI also one of the significant cause for infertility. Conclusion: Therefore, identifying the risk factors and proper treatment on time along with policy makers providing facilities to resolve the infertility could possible diverse this alarming increasing trend of infertility.