Heparin-induced skin reaction is a recognized complication of subcutaneously administered, unfractionated heparin, and has recently been described in association with the use of two LMWH preparations, Fragmin and Fraxiparin. We describe the case of a 25-year-old woman in whom characteristic skin lesions were induced on separate occasions by unfractionated heparin, Fragmin and a third preparation of LMWH, Clexane. This case demonstrates that substitution of one preparation of heparin for another does not prevent recurrence of skin reaction in susceptible patients. Alternative anticoagulants should be considered in these cases.