Lactose absorption capacity was examined in 414 apparently healthy, adult Pakistani subjects. In a subgroup of 44 subjects, the lactose tolerance test was performed using both blood glucose and breath hydrogen determination. The remaining 370 probands were examined using a field version of the breath hydrogen test. In the total sample of 414 probands, 248 lactose malabsorbers were identified (60%). This result differs considerably from previous reports of very low frequencies of lactose malabsorption in Pakistan and neighbouring areas.