Aim: To assess the clinical and radiological characteristics of the posterior prolongation of the cartilaginous nasal septum, an under-utilised source of autologous cartilage for nasal reconstruction. Materials and methods: Consecutive patients undergoing primary, external approach rhinoplasty were included. The septal cartilage was assessed intra-operatively prior to routine harvest. Cartilage use was recorded and post-operative cosmesis noted. Computed tomography scans from a separate patient group, with no septal surgery, were used to assess septal cartilage dimensions. Results: Of the 25 rhinoplasty patients studied, 24 had harvestable septal cartilage, with a posterior prolongation mean length ± standard deviation of 24.3 ± 8.40 mm, mean height of 4.33 ± 0.34 mm and mean width of 1.1 ± 0.35 mm. The mean post-operative cosmesis score was +2.41 ± 0.71 at a mean follow up of 45 ± 8.7 weeks. All 25 radiology patients had visible posterior prolongations on computed tomography (mean length, 18.1 ± 5.1 mm; mean height, 4.2 ± 1.1 mm; mean width 1.5 ± 0.63 mm). Conclusion: Harvesting of the posterior prolongation would increase by 25 per cent the cartilage area available for autologous grafts. Endoscopic guidance aids this process. Cartilage is most commonly used for overlay grafts, with good cosmesis. The posterior prolongation is demonstrated on computed tomography, although dimensions may be underestimated.