Hyperemesis gravidarum or pernicious vomiting of pregnancy affects between 0.3% and 2% of all pregnant patients. The objective of this paper is to review current literature pertaining to epidemiology, etiology, symptomatology, complications, treatment, and perinatal outcome of patients with hyperemesis gravidarum. We performed a MEDLINE search of the English literature from 1966 through January 2000 utilizing the keywords: hyperemesis gravidarum, nausea and vomiting, and pregnancy. Current data pertaining to epidemiology, etiology, clinical manifestations, differential diagnosis, complications, various treatment modalities, subsequent perinatal outcome and recent developments are presented. Review of the literature supports that hyperemesis gravidarum is a multifactorial disease in which pregnancy-induced hormonal changes associated with concurrent gastrointestinal dysmotility and possible Helicobacter pylori infection function as contributing factors. Therapeutic key elements are mainly supportive in conjunction with antiemetic medication. It appears perinatal outcome is unaffected.