Objective: To determine whether vacuum extraction technique is associated with an increased risk of herpes simplex virus (HSV) infection in infants born to asymptomatic mothers. Patients and Methods: We reviewed the charts of all infants born at the Edith Wolfson Medical Center and admitted to the hospital's neonatal intensive care unit from January 1999 to June 2002 diagnosed with HSV infection. Results: During the study period, 6953 infants were delivered at our institution and 11 infants had HSV infection. The prevalence of neonatal HSV infection was 1.6 per 1000 live births. In 699 infants, vacuum extraction was used for delivery. Five out of the 11 infants delivered vaginally by vacuum extraction developed HSV infection at the site of the vacuum extractor application. They were born to mothers who were asymptomatic at delivery and had no history of HSV genital infection. HSV type 2 was isolated from the vesicular fluid in all infected infants delivered by vacuum extraction, and none had central nervous system involvement. The prevalence of neonatal HSV infection in vacuum-assisted birth was seven per 1000 live births as compared to 0.95 in 1000 in infants delivered vaginally of by cesarean section (p<0.0001). The relative risk of HSV infection in infants born in vacuum-assisted births was 7.45 (95% confidence interval (CI) 1.99 to 27.42, p = 0.001). All patients were treated with intravenous acyclovir and no recurrences of HSV infection have been noticed at follow-up. Conclusions: Laceration of the fetal scalp by vacuum extraction technique may enhance the acquisition and the early appearance of cutaneous infection in infants exposed to HSV shedding in the genital tract of asymptomatic mothers, as the virus gains access through the lacerated scalp.