A retrospective chart review was conducted at two regional poison centers to determine the clinical outcome of boric acid ingestions and to assess the relationship between serum boric acid levels and clinical presentation. A total of 784 cases were studied; all but 2 were acute ingestions. No patients developed severe manifestations of toxicity, and 88.3% were entirely asymptomatic. The most common symptoms were vomiting, abdominal pain, and diarrhea. Lethargy, headache, lightheadedness, and atypical rash were seen less frequently. Boric acid levels were obtained in 51 patients and ranged from 0 to 340 micrograms/mL. Blood levels were 70 micrograms/mL or more in 7 patients; 4 remained asymptomatic, whereas the other 3 had nausea or vomiting. Dialysis was performed in 4 of these 7 patients, only 1 of whom had symptoms (vomiting). On the basis of data from 9 patients, the mean half-life of boric acid was determined to be 13.4 hours (range, 4.0 to 27.8). Hemodialysis in 3 patients significantly shortened the half-life compared with pre- and postdialysis half-lives. Our results suggest that acute boric acid ingestions produce minimal or no toxicity and that aggressive treatment is not necessary in most patients.