ABSTRACT Objective To determine the association of a scored patient-generated Subjective Global Assessment with mortality and length of hospital stay in cancer patients. Methods Cross-sectional study carried out between July and September 2014 using secondary data collection using data from 366 medical records of patients admitted to a hospital recognized as a cancer center of excellence. The present study included patients with hospital stay over than or equal three days and minimum age of 20 years. The patient-generated Subjective Global Assessment scores were calculated and compared with the patients’ clinical and anthropometric characteristics and outcomes (death and long length of stay in hospital). Results Of the 366 patients evaluated, 36.0% were malnourished. The presence of malnutrition, according to the scored patient-generated Subjective Global Assessment, was statistically associated with the presence of metastasis (52.4%). On the other hand, malnutrition, according to the body mass index in adults (55.8%) and in older elderly patients (54.2%), was associated with death (55.0%). The adjusted logistic regression model showed that the following factors were associated with prolonged hospitalization: early nutritional screening, presence of severe malnutrition, radiotherapy and chemotherapy, and surgical procedures. As for mortality, the associated factors were: male reproductive system tumor, presence of metastasis, clinical treatment, prolonged hospitalization, and the presence of some degree of malnutrition. Conclusion The patient-generated Subjective Global Assessment score is an important risk marker of prolonged hospitalization and mortality rates. It is a useful tool capable of circumventing significant biases in the nutritional evaluation of cancer patients.