Background: Hypertensive disorders of pregnancy (HDP) complicate 10% of pregnancies and are responsible for 14% of maternal deaths worldwide. HDP is the second leading cause of maternal and neonatal mortality and morbidity in the world. Most maternal deaths can be prevented by timely identification, management and referral services by health professionals working in a supportive environment. Auxiliary Nurse Midwives (ANMs), are first accessible village-level health workers in the community who are the grass-roots workers in the national health care organization. Their services may help communities in achieving the targets of maternal and child health programmes. Thus, it is very essential to strengthen the knowledge of the primary level health workers in improving the perinatal outcomes among women and children. Aim of the study was to measure the effectiveness of educational intervention on knowledge regarding Hypertensive Disorders of Pregnancy among Auxiliary Nurse Midwives in selected health care centres, West Bengal.