Aim: The aim of the present study was to study the menstrual pattern and various menstrual problems among urban adolescent girls. Material and methods: This was a cross sectional study conducted in the department of gynaecology and obstetrics in Patna Medical College and Hospital, Patna, Bihar, India, from August 2014 to July 2015. 120 adolescent girls selected randomly who presented with menstrual problems in gynaecology OPD were included in this study. Total of 120 girls were asked to fill up a questionnaire which included questions like age of menarche, pattern of menstruation, durationand amount of flow, number of pads used. Result: This study shows Majority of girls (60.83%) attained their menarche between 10-13 years of age and remaining 39.33% were in the age group of 14-16 years. Majority of girls had problem of Oligomenorrhea (60%). 31.67% of girls had normal cycle length of 28-35 days and only 9.17% had frequent bleeding with cycle length less than 28 days. But duration (3-5 days) and quantity of flow was normal in maximum girls 79.17% and 62.5% respectively. Excessive flow with passage of clots or duration of flow for more than 5 days was noted in 20.83% and 13.33% of girls respectively. Only 7.5% had flow for less than 2 days. Menstruation is associated with multiple morbidities, in our study majority of girls had problem of oligomenorrhea (60%) followed by dysmenorrhea (51.67%) and menorrhagea (22.5%). Dysmenorrhea was the main reason of absenteeism from school (with 45.71%). Menorrhagia along with dysmenorrhea was second most common reason (14.28%) for absenteeism from school. Third main reason was menorrhagia, reported by 22.86%. Conclusion: This study highlights the need of awareness of menstruation and related problems among the adolescent girls to avoid future reproductive health problems.