Tuberculous infection was first introduced to the majority of the Inuit (Eskimos) in the first half of this century. In the 1950s tuberculosis became a grave problem with the mortality rate approaching 1% per annum and the incident rate almost 3%. The annual risk of infection has been estimated at 25% per annum. These are probably the highest rates recorded anywhere in the world in the 20th century. Some 20-30 years ago, an intensive case-finding programme as well as a treatment programme began in all three jurisdictions where the Inuit live (northern Canada, Alaska and Greenland). The preventive measures differed; Alaska relying mainly on chemoprophylaxis and Greenland on BCG vaccination, while Canada adopted both measures. Over the last 20 years, the rates fell rapidly with the mortality rate approaching zero, and the morbidity (incidence) rate falling (Canadian Inuit) by the record 14% per annum. The high rates in the Inuit were, in part, an expression of the lack of 'natural' resistance acquired by other races through the exposure to tubercle bacilli for many generations. Over-crowding in igloos and frequent starvation among those Inuit who relied on cariboo meat, undoubtedly contributed a great deal to the gravity of the problem. The rapid decline of the rates is without doubt primarily caused by the intensive tuberculosis programme and the compliance of the Inuit with the demands of this programme; better housing and in some cases, improved nutrition doubtlessly also played a part.