We undertook a retrospective study to evaluate the efficacy, safety, and suitability of tribromoethanol (0.2 ml/10 g body weight of a 1.2% solution) as a surgical anesthetic in mice. We compiled records of embryo transfer during a 2.5-year period (1989-1991) and examined mice subjected to several other procedures requiring anesthesia. We documented a low rate of mortality and morbidity (< 1%) and the absence of any significant abdominal adhesions or inflammatory response. The rapid induction and recovery, adequate surgical plane of anesthesia, and lack of complications make this anesthetic effective and simple to use. Precautions necessary to prevent decomposition of the anesthetic, storage in the dark at 4 degrees C, were minimal.