A retrospective review of our prospectively collected database was undertaken and the functional and oncologic outcomes after Type One pelvic resections for bone tumours of the ilium and sacrum were analyzed. Seventeen patients were identified with a minimum followup after resection of twelve months. In seven patients the bone defect was reconstructed, with no reconstruction in the remaining ten patients. The functional/oncologic outcomes of the two groups are similar, however patients without reconstruction had fewer complications and less dependence on walking aids suggesting that reconstruction may not be justified. Management of defects created by Type One pelvic resections of large iliac bone tumours remains controversial. We reviewed the functional/oncologic outcome following resection with and without reconstruction. Similar functional/oncologic outcome was achieved in both groups suggesting that reconstruction is not justified. A retrospective review of our prospectively collected database was undertaken analyzing functional/oncological outcome of seventeen patients with Type One pelvic resection. Minimum follow up was twelve months (12–96). Outcome data was available on 8/10 patients managed without reconstruction (WOR), with residual ilium collapsing back onto sacrum, and on 5/7 patients with bone graft reconstruction (WR). Average age thirty-three years (WOR) and 48yrs (WR), (p=0.04), with average maximal tumour dimensions of 12cm and 9cm (p=0.1). The most frequent diagnosis was chondrosarcoma. The WOR group average TESS, MSTS 87 and MSTS 93 scores were respectively 73%, 18/35 and 58% at an average of 50 months (24–96) compared to 69%, 21/35 and 51% at an average of 37 months (12–60) for the WR group. 33% of WOR and 20% of WR patients did not require walking aids. Infection or wound necrosis occurred in 40% of WOR patients and 57% of WR patients. No local recurrences. The perceived advantages of no reconstruction are shorter operating times, reduced incidence of complications and improved functional outcome due to medialization of the weightbearing axis in the absence of hip abductors. The oncologic/functional outcomes of both groups were similar but in those not reconstructed there was a lower incidence of complications and walking aids.