Background:Infertility is a life crisis affecting patients from all around the world. It is a disease of the reproductive system dened by the failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse. Worldwide, its prevalence is approximately 8-12%. Aim:To determine the causes and clinical pattern of infertility in couples based on clinical and laboratory nding Methods: It was hospital based observational study carried out in the department of Obstetrics and Gynaecology of Katihar Medical College and Hospital, from Feb 2019 to Jan 2020. 300 women were selected for the study with the diagnosis of infertility and 36 of them were lost to follow up so 264 women were enrolled in the study Result: Out of 300 women, 264 had all the data and they participated in the study. Maximum women (50%) were in age group 20-29 yrs. The median duration of marriage was 5 yrs. Primary infertility was in 70% women and 30% women presented with secondary infertility. Female factor was found in 48.1% cases, 15.2% cases had only male factor, 28% having both male and female factor whereas 8.7% cases were with unexplained infertility. Features of polycystic ovaries and ovulatory dysfunction were found in 14.4% women. Adnexal pathology was seen in 10% cases, uterine broid detected in 10.6% cases and uterine anomalies were found in 1.5% cases. High level of TSH (TSH≥4) were found in 32 (12.1%) women and 14 women (5.3%) diagnosed with hyperprolactinemia (≥25ng/ml). Approx. 3.4% women were found to have high level of FSH≥10, whereas LH was raised in 2.3% cases. 14.4% male had abnormal semen parameters. Common abnormalities were azoospermia 6% and oligozoospermia in 3.8% and asthenospermia in 4.5% cases. Conclusion: Primary infertility cases are more common with female factor predominance over male factor. Ovulatory dysfunction, tubal pathology, hormonal imbalance and abnormal semen parameters were main contributing factor for infertility. Male and female both factors are responsible for infertility. So, both partners should be counselled and investigated properly.