Aims. To compare the differences between patients with inflammatory cardiomyopathy (ICM) with and without improvement in left ventricular (LV) systolic function and to identify the relevant predictors of LV improvement. Patients and Methods. The study included 63 patients with biopsy-proven ICM and heart failure symptoms of at least NYHA II, symptom duration <= 6 months, LV ejection fraction (LVEF) <= 40% assessed by echocardiography and presence of >14 mononuclear leukocytes (LCA+ cells)/mm2 in biopsy samples. Patients were evaluated at baseline and after 6 months. Results. In the group with LVEF improvement of >= 10% (I+ group, n = 41), LVEF increased from 24 ± 7% to 47 ± 8% (P < 0.001). In 22 patients (group I-), there was no or minimal LVEF increase (< 10%). In the I+ group, there were more LCA+ cells/mm2 at baseline (25.1 ± 16.5 vs. 18.5 ± 4.4 cells/mm2; P = 0.032) and a more significant decrease in LCA+ cells in the follow-up (reduction of 13.6 ± 14.3 cells/mm2 vs. 5.0 ± 7.7 cells/mm2 in the I- group; P = 0.009). The univariate logistic regression showed a possible association of number of LCA+ cells, LV end-diastolic diameter and N-terminal fragment of pro-brain natriuretic peptide (NTproBNP) value with LVEF improvement. In the multivariate analysis, only NTproBNP at diagnosis was confirmed as an independent predictor of LVEF improvement (OR=1.2; 1.003 to 1.394; P = 0.046). Conclusion. The LV systolic function improvement was observed in 65% of the patients. In these patients, the number of inflammatory cells at baseline was higher and decreased more but the higher baseline NTproBNP value was the only independent predictor of LVEF improvement.