Blood samples were collected by jugular venipuncture from 15 dairy heifers and the blood platelets were counted by manual methods. The platelets were found to be uniformly distributed across the rows, columns and sides of a Neubauer haemocytometer, and it was shown that counting any 10 squares on either side of the haemocytometer and multiplying by a constant factor would accurately predict the total platelet count. This procedure would greatly reduce the time required to count large numbers of platelets per sample, and reduce errors due to the fatigue associated with counting large numbers of samples.