An epidemiological survey on tuberculosis was conducted in the Abha and Baha areas of Saudi Arabia, to determine the prevalence of tuberculosis infection in 985 subjects. Individuals were interviewed and given a Mantoux test. Twenty six percent (26%) of all subjects who received no BCG vaccination had a positive Mantoux reaction (greater-than-or-equal-to 10 mm induration); the percentage was lower in age group 5-14 (4%) and higher in age group 45-64 (52%). The prevalence in age group 5-14 puts Abha and Baha cities between low prevalence (2%) and middle prevalence (14%) countries, according to the classification of the International Union Against Tuberculosis. Positive Mantoux reactions were significantly more common in males than in females (p < 0.05), urban residents compared to rural ones (p < 0.001), and non-Saudis compared to Saudis (p < 0.001). However, education and occupation had no significant effects. Similarly, no significant effects were produced by presence of cough, sputum production, fever, chest problems and family history of tuberculosis on this prevalence.