OBJECTIVES: : Population aging has brought greater demand for admissions of patients with chronic diseases fleeing the routine therapeutic goals. The objective of this study is to evaluate the application of Karnofsky Performance Scale (KPS) to identify patients who need palliative care and avoiding therapeutic futility. METHODS: An observational vertical prevalence study made in June 2014 of clinical patients admitted in a public hospital in São Paulo city, by applying a brief and objective questionnaire directly to patient's physicians in order to obtain a diagnosis of the clinical situation aspects, based on KPS. RESULTS: According to the analyze of  259 questionnaires/patients (Female: 111 and male: 148) from all adult inpatient sectors in the hospital (medical wards, surgical wards and intensive care unit), we found: a) 62.55% with KPS ≥ 50 (without advanced disease); b) 2.70% with KPS = 40 (disease in progression to advanced); c) 1.16% with KPS = 30 (advanced disease, with no expectation of cure, unless performing organ transplants); d) 15.44% with KPS = 20 (advanced disease without an effective cure or treatment that can modifies the disease); e) 17.76% with KPS = 10 (death prediction in the present admission). Only one patient could not be classified. About 57% of patients were older than 50 years. CONCLUSIONS: The KPS analysis showed 37.45% of the patients were with advanced disease condition and without possibility of cure who should be better treated in palliative care environments with more specific conditions for them, without using  numerous and expensive drugs and procedures which only cause more suffering to these group of patients. To disseminate and applying the knowledge in palliative care will certainly contribute to a more rational use of therapeutic resources.