In the present study we evaluated lactose malabsorption (LM) after ingestion of three dairy products in 53 healthy institutionalized elderly people. A preliminary screening with milk (250 ml, 11 g lactose) was carried out to select the LM subjects using the H2 breath test. The effect of consuming an equivalent amount of lactose contained in yogurt and fermented-then-pasteurized milk (FPM) was then assessed in LM subjects. Results indicated that 36% of the elderly population studied was considered as LM and that breath H2 excretion was significantly higher after ingestion of milk than after ingestion of yogurt. This beneficial effect was partially eliminated when FPM was tested. Moreover, breath H2 excretion was significantly higher (p less than 0.05) 3 hours after ingestion of FPM compared to the normal yogurt. These results demonstrate a high prevalence of LM in the elderly and confirm the positive effect of yogurt on lactose absorption, whereas pasteurized yogurt did not cause the same effect.