The two percutaneous tuberculin tests Tine test (TT) (old tuberculin) and Monotest (MT) (PPD-tuberculin) were compared simultaneously with the standard intradermal reaction (Mantoux [MX] 1:1000 = 10 EPPD-RT23-tuberculin) in 119 unselected 16-81 year old outpatients (general medicine) in an open trial. The tests were read after 48 and/or 72 h. Indurations of greater than or equal to 10 mm (MX), greater than or equal to 2 mm (MT) and greater than or equal to 5 mm of one papule or confluescent papules (TT) were considered to be positive. 6-9 mm for MX and 2-4 mm for TT were considered doubtful. The overall agreement with MX (69.7% positive, 27.7% negative reactions) was 92.4% for MT and 68.1% for TT. Regarding sensitivity (false negative reactions), MT provided far better results than TT (8.4% vs. 44.6%). TT performed equally well when the doubtful reactions were reclassified as positive (8.4% false negative). It is recommended that the limit for a positive TT be lowered to greater than or equal to 2 mm, as other authors have suggested. MT always produced easily palpable and measurable indurations, whereas the borderline TT reactions (2-4 mm) were difficult to read and the size of the four papules varied considerably in most instances. Only MT showed significantly more positive readings after 72 h compared to 48 h. MT was better tolerated subjectively than TT with regard to application and skin reaction. The Monotest can be recommended as tuberculin screening test for general practice.