In this study we investigated the reproducibility of 111-In-platelet survival time (PST) measurements and of plasma levels of beta-thromboglobulin (beta-TG) and platelet factor 4 (PF 4) in 30 patients (median age: 60.5 years) with arteriographically proven peripheral arterial occlusive disease (PAOD) in a chronic stable phase. PST calculated by both the weighted mean - WM - (1. investigation: 187.1 [median] hours - repeat investigation: 188.3 hours) and multiple hit - MH - model (181.4----177.4 hours) demonstrated only a small spontaneous variation. The median coefficient of variation (CV) was 3.0 (WM) and 3.2 (MH), respectively. The reproducibility of beta-TG (CV: 6.1) was also satisfactory. We conclude that the good reproducibility of PST and plasma levels of beta-TG make them well suited to judge the influence of platelet-suppressant drugs on these parameters in patients with PAOD.