INTRODUCTIONAdolescence proves to be the most vulnerable stage in the way of human life cycle after childhood, characterized by accelerated growth and development with a change from childhood to maturity. 1 The adolescent word is taken from Latin word 'adolescence' which means to grow into maturity. 1For girls, menstruation is a physiological process which unprecedented to women that begins in puberty. It is periodic discharge of blood and mucosal tissue from the uterus for 4-5 days (average) occur regularly every 28-30 days of cycle. 2 In India there are over 355 million menstruating women and girls but millions of girls across the country still facing significant problems to a comfortable and dignified experience with menstrual hygiene management. 3 In India about 88% of women use homemade products (e.g., old cloth or rags) during their menstrual period. The main reasons for using cloth-based product are: personal preference and familiarity, lack of approach to or affordability for good-quality commercial sanitary pads, and lack of adequate information about pads. Some girls also use locally made cotton cloth. The reproductive tract infection (RTI) incidence was 70 percent more common ABSTRACT Background: In India menstruation is generally considered as unclean. Orphanage girls are vulnerable group in our society. The unfailing support and a constant check of orphan girls during menstruation are usually absent. The objective of the study was to assess the knowledge and practices regarding menstrual hygiene among adolescent girls residing in selected orphanages of Haryana. Methods: A descriptive survey was conducted on 150 adolescent girls residing in selected orphanages of Haryana. Purposive sampling technique was used to select the adolescent girls for study. The data was obtained by structured knowledge questionnaire and structured practice questionnaire. Results: SPSS version 20 was used for statistical analysis. The result of the study indicated that more than half of adolescent girls (62.7%) were in age group of 12-15 year. Half (50.7%) of adolescent girls had age of menarche at 12 year. Only 16% adolescent girls had good knowledge regarding menstrual hygiene. 95.3% were using sanitary pad during menstruation. Conclusions: The present study concluded that adolescent girls had poor knowledge of menstruation and menstrual hygiene.