SummaryAttempts were made to detect porcine thrombocyte antibodies by three techniques. No antibodies were detected by immunodiffusion; hetero‐antibodies were detected by both the fluorescent antibody and thrombo‐agglutination techniques; but iso‐antibodies were only detected by thrombo‐agglutination. With the latter, however, there were ill‐defined end‐points which made the interpretation of negative results difficult. It was therefore suitable only for positive reactions of str