This study aimed to assess the knowledge and practices regarding menstrual hygiene among adolescent girls (age-group 13–18 years) in rural areas of Bishnugarh, Hazaribag, Jharkhand. A total of 100 female adolescent respondents were randomly selected for data collection. A pretested schedule was employed to gather information on their general profiles, anthropometric assessments, 24-hour dietary recalls, knowledge, and practices related to menstrual hygiene. The study found that a substantial proportion of respondents (78%) fell within the 16–18 age-group, while 22% were aged between 13 and 15. Additionally, 99% of the respondents identified as Hindu, with 72% belonging to nuclear families and 28% to joint families. In terms of education, 44% were in the 11th grade, 23% in the 12th grade, 22% in the 10th grade, and 11% in the 9th grade. Furthermore, 67% of the families engaged in business, while 33% were involved in agriculture. The study revealed that 95% of the respondents’ mothers were illiterate, and 93% of the respondents had a non-vegetarian diet, while only 7% were vegetarian. Anthropometric assessments indicated that 42% of respondents had a normal body mass index (BMI), while 10% and 26% experienced Grade III and Grade I undernutrition, respectively. Dietary patterns showed that cereals, fats, and oils were consumed daily by all respondents, with lower frequencies of pulse, fruit, meat, and poultry consumption. Most respondents consumed roots and tubers daily. Regarding knowledge of menstruation, 56% of girls were aware of it before their menarche. The study found that 49% of girls experienced menarche at the age of 13, with 31, 15, and 5% experiencing it at ages 14, 15, and 16, respectively. Friends and mothers were identified as the primary sources of information about menstruation. In terms of menstrual hygiene practices, 40% of girls used cloth, 35% used sanitary napkins, and 25% used both cloth and sanitary napkins as menstrual absorbents. Most respondents (52%) changed their absorbent every 3 hours during the first 2 days of menstruation, and 92% changed their undergarments daily. The majority (91%) bathed daily, 92% washed their hands properly after changing the absorbent, and only 22% cleaned their pubic hair regularly. Among girls who washed their vaginal area daily during menstruation, 62.8% used soap for washing. Additionally, 54% of girls reported lower abdominal pain, and 17% reported fatigue and weakness during menstruation. Only 20% of respondents were aware of restrictions during menses. Notably, girls using cloth as menstrual absorbents were highly prone to menstrual morbidities, with 62.5% experiencing both fever and irritation in the vaginal area. Among those using sanitary napkins, 25.7% suffered from both fever and irritation and among those using both cloth and sanitary napkins, 16% experienced these symptoms. The study did not find significant results in the Analysis of Variance (ANOVA) tables for various nutritional aspects. In conclusion, this study highlights significant issues related to poor knowledge of menstruation biology, the presence of menstrual symptoms among girls, and low usage of sanitary napkins. It underscores the need for adolescent girls to receive accurate and adequate information about menstruation and its proper management. Formal and informal channels of communication, such as mothers, sisters, and friends, should be utilized to provide this information.