The article briefly describes the various methods that are available for diagnosing hypolactasia. Special attention is drawn to the fact that different methods are useful at different levels of the health care organization. When the test result indicates lactose malabsorption, general malabsorption should be excluded by a glucose-galactose tolerance test, for example. If the glucose-galactose tolerance test produces a normal result, it can be assumed that the patient has primary adult-type selective lactose malabsorption. The possibility of secondary lactose malabsorption must be excluded according to the principles described by Villako & Maaroos (104).