Since 1990 the incidence rate of tuberculosis has been increasing in Storstroem County, both in persons born in Denmark and in immigrants/fugitives. The increase in patients born in Denmark has been seen mainly among younger males. Subtypes LC2 and C2 were selected for further investigation of the sources and modes of infection, as the number of infected patients was increasing and the index patients were well known. All contacts were traced and investigated according to the Danish recommendations. In total, 49 patients were treated, and 63 other persons shared their households. By comparison of infected contacts in households with infected patients who had shared a water pipe with a known patient, risk rates of 0.76 and 0.73 were found. When a positive Mantoux test was included, the figures were 0.60 and 0.64, respectively. As risk rates for the two modes of infection were the same, we recommend that the use of water pipes should be included in the routine search for carriers of infection.