The early and accurate treatment of ARF remains an important problem in the management of critically ill patients. Despite recent technological diagnostic advances, the autopsy remains an important complementary tool for identifying and understanding diseases. Autopsy studies have shown important differences between autopsy findings and the antemortem clinical diagnoses. [11] [12] [13] Such diagnostic disagreement can vary from 10% to 90%, depending on the disease and the population involved. [4] [5] [6] [7] [8] [9] [10] [14] [15] [16] [17] [18] [19] These discrepancies may be attributable to different clinical manifestations of a single disease or to poor-quality medical care. 4 Recently, ARF was reported to be one of the leading causes of morbidity and mortality in critically ill patients. 4, 9, [14] [15] [16] In this study, we observed a high prevalence (17.7%) of ARF patients. Most of the study patients were males (57%), and the mean age was 52 years. Others studies have shown similar results. 4, 9, [14] [15] [16] A retrospective study carried out between 1996 and 2002 in 58 patients with DAD diagnosed by surgical lung biopsy found that 52% of the patients were male and that the mean age was 61 years. 20 We observed a single disease in 38% of the patients with ARF and two or more diseases in 62% of the patients. The high prevalence of multiple diagnoses illustrates the complexity and critical status of the patients that presented with ARF as the cause of death; it may indicate the need for a different therapeutic strategy with these patients. [21] [22] Our study specifically showed that the patients who developed ARF had underlying diseases such as BBP (33.9%), cancer (28.1%), sepsis and septic shock (14.3%), liver cirrhosis (13.6%), HIV/AIDS (10.4%), pulmonary embolism (9.0%), acute myocardial infarction (4.7%), brain stroke (4.4%), chronic kidney failure (4.4%), and diabetes mellitus (4.1%). Infectious diseases were the most common diagnoses, as has also been described by other authors. 6, 9, [14] [15] [16] [17] [18] [19] [20] 23, 24 Interestingly, these findings are not consistent with our previously published study in 2008 that reported related cases of ARF in autopsies from 1990 to 2000 only; it reported the following associated diseases or complications in descending order: HIV/AIDS (31.4%), BBP (21.8%), sepsis and septic shock (11.7%), liver cirrhosis (11.5%), pulmonary embolism (5.7%), acute myocardial infarction (5.5%), brain stroke (4.6%), tuberculosis (3.6%), cancer (2.3%), chronic kidney failure (1.9%), and leukemia (0.2%). 22 BBP was present in 33.9% of the patients and was the most frequent pulmonary complication found during autopsy. Frequently, the ARF patients had BBP as the initial cause of pulmonary disease, but BBP often occurs as a complication of other pathologies, usually in immunocompromised and intubated patients. Other studies have described similar findings and reported BBP as the most common disease in ARF patients. 20,23-25 Gross et al 25 analyzed 234 autopsies of elderly patients and found that 33% of them had BBP, which is exactly the same prevalence observed in our study but in an elderly-only population. 25 Cancer was the second most important complication diagnosis in our study; it was present in 28.1% of the autopsies. This incidence rate was higher than that observed in other studies. 25 The most interesting observation was the increase compared with the incidence found in our previously published survey (2.3%). 22 This finding suggests that the number of diagnoses and the severity of cancer presentations have increased. These patients had been exposed to immunocompromised conditions from the use of quimioterapic agents and anorexia. Both these conditions increase the risk of associated infections, which are one of the major causes of death in this population. 20, 26 Consequently, pulmonary manifestations are one of the most common causes of death in these patients; there is a high incidence of BBP, including atypical bacterias. 20, 25, 26 In this study, HIV/AIDS was present in 10.4% of the patients with ARF. Pulmonary involvement has been reported in between 80 and 94% of the patients with HIV/ AIDS. The classical evolution of patients with HIV/AIDS to ARF and its importance have been reported in several other studies. [11] [12] [13] 21, 22 As in patients with cancer, immunocompromised conditions substantially increase the risk of infection. Associated bacterial BBP is the major cause of respiratory failure, but tuberculosis, cytomegalovirus and Pneumocystis jiroveci pneumonia are also important causes of pulmonary commitment. [11] [12] [13] 21 In contrast to our previous publication, the rate of HIV/AIDS infection has declined over the last ten years from 16-31% to only 10.4%. 21, 22 Modern diagnostic methods, antibiotics and antiretroviral therapy have been reported to be the major causes of this modification of the HIV/AIDS prevalence in critically ill patients. 21 We observed liver cirrhosis in 13.6% of the autopsies in this study; a similar association in ARF patients was not found in the literature. We realize that liver cirrhosis can result in an immunocompromised or inflammatory status similar to that of other pathologies and predispose patients to infectious diseases.