Introduction: In 2050, we estimate that the population of individuals who are 90 years of age or older will be five times higher than that in 2010. Among elderly people, the disease process can contribute to a worsening nutritional status. This article aims to examine the associations among nutritional status and initial diagnoses, muscle mass, routes of feeding, and clinical outcomes. Despite the progressive increase in this population and their particularities, few studies have been conducted among nonagenarians. Methods: This was a cross-sectional study that included patients over 90 years old admitted to Hospital Sírio Libanês. The following parameters were assessed: calf circumference (CC), body mass index (BMI), routes of feeding and medical diagnosis. Nutritional screening was performed using the Mini Nutritional Assessment (MNA). Results: A total of 79 patients were assessed, and they had a median age of 92 years, a median BMI of 22.6 kg/m2 and median hospital stay of 13 days. A total of 59.5% of the patients (n=47) were female. The frequency of malnutrition (as assessed by the BMI) was 54.4%. There was a positive relationship (71.4%) between CC <31 cm and underweight (as assessed by the BMI) (p=0.032). Malnutrition (classified using the MNA) was significantly associated with dysphagia (77.4%) (p=0,003), the use of supplements (p=0.002) and enteral nutrition therapy (p=0.005). Mortality (25.8%) was also significantly related to malnutrition, showing that nutritional status contributed to poor clinical outcomes in patients (p=0.042). Conclusion: Dysphagia had a positive relationship with malnutrition because it is a condition that affects food intake. The use of supplements and a higher indication for enteral nutritional therapy both had a positive relationship with malnutrition because they are conducts indicated to improve nutritional status, showing that specific nutrition assistance strategies for this age group can contribute to improved nutritional status in nonagenarians.