A descriptive study was conducted to assess the knowledge and attitude regarding premenstrual syndrome of adolescent girls from selected schools of Ahmedabad, Gujarat. The main objective of the study was to assess the knowledge and attitude regarding PMS of adolescent girls from selected schools of Ahmedabad, Gujarat. The ‘General System Model’ adopted from Ludwig Von Bertalanaffy was used as the conceptual frame work. A quantitative approach with descriptive study design was used to achieve the objective of the study. The samples consisted of 150 students of selected schools of Ahmedabad. The simple random sampling technique was use to collect the sample. A structured questionnaire was used to assess the knowledge and attitude scale was used to assess attitude regarding premenstrual syndrome among adolescent girls. The tool was validated by the experts. Cronbach alpha was used to establish the reliability of tools. The tool was found to be valid and reliable. Data gathered was analyzed and interpreted using both descriptive and inferential statistics. The study shows 15.5% adolescent girls having adequate, 81% adolescent girls having average and 3.5% having inadequate amount of knowledge regarding premenstrual syndrome and 55.5% adolescent girls having good attitude, 44.5% adolescent girls having average attitude and no participant having poor attitude regarding premenstrual syndrome. There was positive co-relation between knowledge and attitude regarding premenstrual syndrome among adolescent girls. Based on the findings the following recommendations were proposed for the future research: A similar study can be replicated on a large sample with the similar baseline characteristics.