We aimed to determine long-term prognostic role of echocardiographic and hematologic parameters in heart failure patients complicated with incidental pleural effusion (PE) diagnosed during echocardiographic evaluation. The study was performed by evaluating patient records in which PE was incidentally detected during echocardiographic examination in a tertiary teaching hospital between Jan 2002 and Dec 2012. Total 151 patients with heart failure complicated with PE were analyzed. All patients' mortality data were collected from registry center of Social Insurance Institution which is officially responsible for recording all mortality data in Turkey. Detailed echocardiographic and hematologic parameters including creatinine, uric acid, albumin, sodium, potassium, hemoglobin at the time of hospital admission were analyzed. Data from 151 eligible patients were analyzed. We compared patients who died (n = 51) during follow-up with the survivors (n = 100) in terms of patients' echocardiographic and hematological features. Mean duration of follow-up was 71.5 ± 45.6 months. Fifty-one patients (33.8 %) died during this follow-up period. From all echocardiographic parameters only dilated left atrium (LA) diameter was found to be associated with a poor prognosis (p = 0.034). Low albumin, sodium and hemoglobin levels were associated with poor prognosis (p < 0.001, p = 0.002 and p = 0.007, respectively). We showed that dilated LA, as well as low albumin, low sodium and low hemoglobin levels had a worse prognostic significance than patients with normal LA size, within normal limits of albumin, sodium and hemoglobin levels in patients with heart failure complicated with PE determined incidentally by echocardiography.