Pericardiocentesis is a percutaneous drainage procedure performed in cardiac tamponade or a moderate-large pericardial effusion that does not respond to medical treatment. The prognosis varies according to the etiology of pericardial effusion, and the parameters that can determine the prognosis are unknown. In this study, we aimed to find predictors that can determine inpatient mortality in patients who underwent pericardiocentesis and to determine cancer etiology. Method: Ninety-one patients who underwent pericardiocentesis due to moderate-large pericardial effusion or pericardial tamponade were evaluated retrospectively. Baseline characteristics of the patients, their cancer diagnosis before and after pericardiocentesis, pericardial effusion cytology, echocardiographic parameters and laboratory parameters in the baseline evaluation were evaluated. The group with inpatient death (n = 14) and the surviving group (n = 77) were compared with each other. Results: There was no significant difference between baseline demographic characteristics and echocardiographic parameters when the patients with inpatient mortality and survivors were compared; only patients diagnosed with cancer (p <0.001) and patients with malignant cytology (p = 0.041) were statistically significantly higher in the group with inpatient mortality. When patients with inpatient mortality and survivors were compared in terms of laboratory parameters, aspartate aminotransferase (AST) [55 (27-455), 26 (19-45); p = 0.007, respectively], lactate dehydrogenase (LDH) [527 (438-944), 282 (225-381); p <0.001, respectively], C-reactive protein (CRP) [120.5 (19.8-140.7), 36.5 (8.26-86.15); p = 0.016, respectively], NTproBNP [8964 (7780-9432), 1310 (351-4556); p = 0.049] values were significantly higher in the inpatient mortality group than in the surviving group. The presence of cancer (p = 0.001), AST (p = 0.008), alanine aminotransferase (ALT) (p = 0.013), LDH (p = 0.015), CRP (p = 0.046) parameters were detected to be predictors that can be used to predict inpatient mortality in the univariate logistic regression analysis conducted to determine the predictors that could indicate inpatient mortality. Conclusions: Inpatient mortality is high in patients that were detected to have underlying malignancy and pericardial involvement after pericardiocentesis. In the initial evaluation of these patients, simple laboratory tests such as AST, ALT, NTproBNP, LDH, CRP can give an idea about the short-term prognosis of the disease.