Objective. To investigate the prevalence, duration, and etiology of bacteremia following dental extractions performed after a single administration of Chlorhexidine mouthwash. Design and Setting. A randomized, controlled trial performed in a university hospital. Methods. A series of 106 patients with mental and behavioral disabilities who underwent dental extractions under general anesthesia were randomly assigned to a control group or Chlorhexidine group. The exclusion criteria applied were use of antibiotics in the previous 3 months, use of oral antiseptics, any type of congenital or acquired immunodeficiency, and disease that predisposes the patient to infections or bleeding. The Chlorhexidine group had 0.2% Chlorhexidine mouthwash administered for 30 seconds before any dental manipulation. Blood samples were collected at baseline, 30 seconds, 15 minutes, and 1 hour after the dental extractions. Subculture and further identification of the isolated bacteria were performed by conventional microbiological techniques. Results. The prevalence of bacteremia after dental extraction in the control and Chlorhexidine groups were 96% and 79%, respectively, at 30 seconds (P = .008), 64% and 30% at 15 minutes (P <.001), and 20% and 2% at 1 hour (P = .005). The most frequently identified bacteria were Streptococcus species in both the control and Chlorhexidine groups (64% and 68%, respectively), particularly viridans group streptococci. Conclusion. We recommend the routine use of a 0.2% Chlorhexidine mouthwash before dental extractions to reduce the risk of postextraction bacteremia.