Purpose: Large non-age-specific radiotherapy utilisation rate (RTU) studies have demonstrated that actual RTU is below the optimal recommended utilisation rate for both curative and palliative intent radiotherapy indications. The optimal utilisation rate for the geriatric oncology cohort of patients has not yet been determined. The purpose of this research was to examine the actual RTU for patients treated in New South Wales (NSW), Australia as a function of increasing age, and the relationship between RTU and tumour site, travelling distance and socio-economic status. Materials & Methods: NSW Central Cancer Registry data (2009–2011) were linked to the NSW Radiotherapy Dataset (2009–2012). RTU was calculated for patients aged <80 years and ≥80 years. RTU was defined as the proportion of patients receiving at least a single course of radiotherapy within 12 months of a cancer diagnosis. Results: 110,645 patients were diagnosed with cancer, of whom 27,721 received at least one course of radiotherapy. The overall RTU was 25%. RTU for patients aged <80 years was 28% compared to 14% for patients aged 80+ years (p < 0.001). On both univariate and multivariate analysis, increasing age, residential address in disadvantaged socioeconomic areas and increasing distance to the nearest radiotherapy department were associated with a reduction in RTU. Conclusion: Geriatric oncology patients are less likely to receive radiotherapy than their younger counterparts. Some of the reduction in RTU may be justifiable on the basis of limited life expectancy and co-morbidity. Further research is required to determine the co-morbidity adjusted optimal RTU in older patients.