Endoprostheses are now an established technique to reconstruct defects following bone tumour resection. The long-term durability of the reconstruction is excellent, with limb salvage being maintained in the long-term in 91% of patients at 20 years from surgery. The main reasons for secondary amputation were locally recurrent disease and deep periprosthetic infection. Infection remains one of the biggest threats to early failure of reconstructions with endoprostheses. Most series of reconstructions show a periprosthetic infection rate of approximately 10%. Infection most frequently occurs within 12 months from the last surgical procedure; however, the risk of infection is life-long. The commonest pathogenic organism is coagulase-negative Staphylococcus. The most effective treatment for deep infection is two-stage revision, with local treatments having little chance of curing deep infection. Research is on-going into surface treatments with silver and other materials to help to reduce the infection rates.