Deep vein thrombosis is a recognised complication of lower limb cast immobilisation and post operative state immobilisation. A national survey revealed that low molecular weight heparin (LMWH) is the favoured strategy for thromboprophylaxis in the latter context. However, clinicians need to be aware of the fact that the use of LMWH might incur the risk of subsequent development of heparin-induced thrombocytopenia, with its attendant life-threatening thrombotic complications. Some of the patients who develop those complications might be admitted under the care of general physicians, hence the importance of raising awareness of this issue.