Three cases of heparin-induced thrombocytopenia (HIT) are reported that were provoked by daily heparin flushes of central venous access devices. Each case had confounding features that delayed recognition of the problem. A review of the literature revealed only 29 previously reported cases of HIT secondary to heparin flushes. However, the true incidence of this problem is unknown. A high index of suspicion and confirmatory laboratory tests are necessary to make the diagnosis.