This is the case report of a 4 month old Thoroughbred filly, with an unknown medical history, that was diagnosed with thrombocytopenia. The foal was physically healthy with no evidence of bleeding. Initial bloodwork, from EDTA-anticoagulated blood, revealed a platelet count of 24 thou/uL. Differential diagnoses included alloimmune thrombocytopenia, immune mediated thrombocytopenia, EDTA dependent pseudothrombocytopenia and pseudothrombocytopenia from other causes. Subsequent bloodwork demonstrated increasing platelet counts. However, blood submitted to separate laboratories produced variable results. A correlation with of platelet count with the amount of time from collection to processing was observed. The foal's apparent thrombocytopenia resolved without treatment, diagnosis of an underlying disease, or development of clinical signs.