Background: Given the heterogeneity of the overall health status of older patient with cancer, it is recommended to conduct a multidimensional geriatric assessment (MGA) before the establishment of the treatment protocol. Nutritional status is an important part of this assessment, as it is associated to poor health outcomes in older adults with cancer. This study aims to identify factors associated with nutritional status in older adults with prostate cancer. Methods: Cross-sectional study of 538 older adults aged 60 or more, with incident prostate cancer before the beginning of the treatment at hospitals of Brazil's Unified Health System. Nutritional status was evaluated with the Mini-Nutritional Assessment Short-Form version. Socio-demographic and clinical variables, besides some dimensions of the MGA (functionality, comorbidity and emotional condition) were evaluated. We estimated the prevalence of subjects at risk of malnutrition or malnourished and analysed the associations between nutritional status and the independent variables using prevalence ratios and Poisson's regression with statistical significance for p value ≤ 0.05. Results: The mean age of the individuals was 69.11 ± 6.43 years and 27.1% were at risk of malnutrition or malnourished. Presence of depressive symptoms (PR 1.78; 95% CI 1.27-2.50), functional dependence in Basic Activities of Daily Living (PR 1.40; 95% CI 1.01-1.94) and age (PR 1.02; 95% CI 1.00-1.04) were independent factors associated with nutritional status. Conclusion: The high prevalence of patients at risk of malnutrition or malnourished and the association with functional dependence, presence of depressive symptoms and age point the importance to assessment the nutritional status in this population.