Using platelet scintigraphy to evaluate early thrombogenicity, we examined 39 new vascular accesses 4 weeks and 3 months after surgery. We found a significant association between platelet deposition and Doppler flow (P < 0.01) and blood pressure (P < 0.01). Compared with arteriovenous fistulae, prosthetic grafts showed significantly higher platelet uptake (after 4 h: 2.4 +/- 1.1 vs 1.2 +/- 1.1 eU, P < 0.05; after 24 h: 2.1 +/- 1.0 vs 0.6 +/- 0.8 eU, P < 0.01) and a higher Doppler flow (1184 +/- 202 vs 609 +/- 342 ml.min-1, P < 0.001). In 8 of 39 accesses, a thrombosis occurred. Accumulation of activity was not related to shunt thrombosis (specificity 61%, sensitivity 71%). We conclude that 111In-platelet scintigraphy is not suitable for the early detection of shunt thrombosis or for identifying patients at risk.