It is a concern that the population at high risk of HIV infection are relatively unaware of the risk of PCP, resulting in late presentation with the infection. Lack of recognition may lead to delayed diagnosis, delayed treatment, and potentially higher mortality. In this era of HAART and effective chemoprophylaxis, PCP could probably have been prevented in these patients with appropriate prophylaxis and treatment. Our observed mortality rate of 15.2% in the non-HIV group is lower than in several studies, in which rates in the order of 30 to 60% have been reported. However, some studies have also reported mortality rates in the range of 7 to 14%. Previous reports confirm that the interval from admission to the start of PCP-specific treatment and ML 210 diagnosis was significantly shorter in the survivor group than in the non-survivor group. The positive predictive value for survival was.90% when PCP-specific treatment was started within 3 days after admission. Thus it can be seen that early treatment could improve the outcome of PCP. We also observed that time from admission to initial treatment in both groups AF-DX 116 showed a trend towards statistical significance in the univariate Cox analysis, although it is not an independent risk factor. From 2008 to 2012, all-cause mortality and time from admission to initial treatment of NH-PCP patients both show a declining trend. However, the same tendency was not observed in HIV-PCP patients. Etiological diagnosis is not a sensitive test for diagnosing PCP in non-HIV patients, and some critically ill patients have difficultly tolerating invasive procedures. Therefore, it is essential to conduct a non-invasive and high sensitivity examination. PCR technique has advantages of being sensitive and nonivasive. Although PCR can detect colonization and still produce a false positive result, clinicians should take account of clinical factors and be able to make the correct diagnosis. Time from admission to initial treatment was shown to decrease year by year. Possibly the relatively low mortality observed in the present and other recent studies may be attributed to early diagnosis, which in our study was determined to be a marker of favorable outcome.