The efficiency of carbohydrate absorption from two unmodified plain yogurts, a low-fat yogurt and a yogurt produced from lactose-hydrolyzed milk, was compared using the breath hydrogen response in 14 lactose-maldigesters. The maldigesters showed symptoms of intolerance to a standard 360 ml glass of milk containing 18 g lactose. Compared to intact milk, the breath hydrogen response to two varieties of unmodified yogurt and the lactose hydrolyzed yogurt was severely attenuated while the hydrogen response to low-fat yogurt was intermediate. Intolerance symptoms were significantly and equally reduced with all four yogurt products compared to milk. Ten lactose-digesters had a significantly greater efficiency of lactose digestion with 360 ml of milk than the 14 maldigesters; however, except for the magnitude of the maximum rise in breath H2, no inter-group differences were observed in response to unmodified yogurt. We conclude that lactose prehydrolysis adds nothing to the ability to tolerate and digest plain, full-fat yogurts, but it may be useful with low-fat or pasteurized varieties.