Breath hydrogen tests (BHTs) were performed on 340 Burmese village children aged 1–59 months. Normalization (correction of breath H2 values to a constant mean O2 level) eliminated the variations in H2 levels due to sleep, storage temperature, or duration of storage. After a 10 g lactulose test meal, 145 (42.6%) children produced <10 ppm H2 above basal values (non-H2 producers). Of 195 H2 producers, a pattern of breath hydrogen excretion suggesting small bowel bacterial overgrowth (SBBO)—recognized as a transient peak at the 20, 40, or 60 min breath samples following the lactulose test meal and distinguishable from the later colonic peak— was observed in 53 (27.2%), being significantly more frequent in male children, and exhibiting an age-prevalence pattern similar to that of acute childhood diarrhea in these villages. Diarrhea did not alter the state of H2 production (non-H2 producers remain non-H2 producers, and H2 producers remain H2 producers) although the magnitude of peak breath H2 changed.