Introduction: Dysmenorrhea, defined as painful menstrual periods, is one of the most common gynecological complaints and is reported to have significant consequences on quality of life and daily activities. Objective: We aimed to assess the impact of dysmenorrhea on the quality of life and academic performance of adolescent girls at the Classical and Modern High School (CMGHS) of Sangmélima. Methodology: We conducted an analytical cross-sectional study, with data collection over a three-month period (January to March 2025). We included all adolescent girls attending the CMGHS of Sangmélima who gave their approval to participate and whose parents had provided their free and informed consent. Sampling was consecutive and exhaustive. The variables studied were the prevalence of dysmenorrhea, the characteristics of dysmenorrhea, quality of life (World Health Organization Quality of Life - BREF score), and academic performance. Proportions were compared using the chi-square test with a significance level set at 5%. Results: We recruited 318 girls with mean age 16.1 years ± 1.8 years. The prevalence of dysmenorrhea was 57.5%, and in 51.9% of girls with dysmenorrhea, the pain started at the first year of menstruation and was present every month in 65.02%. Common associated symptoms included headaches (52.5%) and depressed mood (51.4%). Regarding quality of life, only 15.3% of affected adolescent girls reported a good quality of life, compared to 52.6% of those without dysmenorrhea. The impact on school was marked by concentration difficulties (77% vs. 31.9%) and increased absenteeism (57.9% vs. 10.4%). Conclusion: As per our study, dysmenorrhea is a very common health condition and significantly impairs the well-being and academic performance of adolescent girls at the classical and modern government high school of Sangmelima.