In a group of 26 patients, all smokers (mean age 56.9 +/- 8 years), with intermittent claudication due to arterial obliterative disease. We investigated some of the haemodynamic, haematologic and clinical parameters before and after a 3 months physical training program. During the training period, none of the patients were given vasoactive, anticoagulant, antiaggregant or other drugs which could affect blood lipid. Patients were instructed to walk for a minimum period of 1 hour daily, in addition to normal everyday activities. Statistically significant differences of claudication pain distance were obtained: 177 +/- 88 m vs 107 +/- 40 m, + 65% (p < 0.001); maximal walking distance: 456 +/- 205 m vs 250 +/- 138 m, + 82% (p < 0.0001) determined during treadmill test at 2 mph up 12% and t/2 peak flow: 30 +/- 11.6 sec vs 46.3 +/- 32.3 sec (p < 0.02), determinated with plethysmographic venous occulsion strain-gauges studies. An important, but not significant decrease of fibrinogen was obtained: 302 +/- 60 mg% vs 328 +/- 57 (p = 0.06), whereas no statistically significant differences were found for the more important haemodynamic parameters: (1) Widsor index determinated before (60 +/- 14% vs 58 +/- 15%) and after (26 +/- 17% vs 26 +/- 17%) treadmill-test with Doppler ultrasound; (2) peak-flow (10.5 +/- 2 ml/100/min vs 10.2 +/- 3); (3) time to peak-flow (17 +/- 10.5 sec vs 19.3 +/- 12.1). We also didn't find any significant differences in total cholesterol (227 +/- 53 mg% vs 228 +/- 48) and haematocrit (43.6 +/- 3.5% vs 43.5 +/- 3.1). Our data demonstrate that physical training is able to significantly increase walking tolerance but non the peripheral blood flow, measured using the plethysmographic and Doppler technique.