We measured blood levels of fatty acids, vitamin A, and trace metals in children undergoing ambulatory surgery for placement of tympanostomy tubes and a comparison group having other ambulatory surgical procedures. We then performed a small, outpatient, secondary prevention study using nutritional supplements chosen on the basis of those blood levels. The study subjects had lower levels of red blood cell eicosapentaenoic acid (EPA) than did adult controls. Consistent with previous reports, the levels of vitamin A were < or = 40 microg/dL for 69% of our subjects, and the plasma selenium levels for children were lower than published values for adults. We then studied one otitis media (OM) season; 8 children (0.8 to 4.4 years of age) received 1 teaspoon of lemon-flavored cod liver oil (containing both EPA and vitamin A) and 1 half-tablet of a selenium-containing children's chewable multivitamin-mineral tablet per day. During this OM season, study subjects received antibiotics for OM for 12.3% +/- 13.4% (SD; p < .05) fewer days during supplementation than before supplementation. Larger, controlled trials are warranted to assess the utility of cod liver oil (of acceptable purity and taste) and a children's multivitamin-mineral preparation containing selenium, both for the prevention of OM and for the acceptance of delayed prescription of antibiotics for this disorder.