Objective: This study aimed to measure the serum concentrations of several cytokines in patients with infective endocarditis (IE), and correlate them with the C-reactive protein serum levels, echocardiographic findings and infecting microorganisms. Methods: Forty-five patients with definite IE according to the Duke’s criteria were included in the study. Ten healthy blood donors formed the control group. Serum levels of interleukin (IL) 1β, IL-6, IL-8, IL-10, IL-12 and tumor necrosis factor-α (TNF-α) were measured and compared between the groups, and also with some clinical and laboratory parameters of IE. Results: Patients with IE had significantly higher serum concentrations of the inflammatory mediators than the control patients. Median IL-12 and IL-1β levels were higher in staphylococcal than streptococcal IE. Except for TNF-α, the levels of all the other cytokines correlated with the C-reactive protein concentrations. In multivariate analysis, IL-10 and IL-12 serum levels remained as independent factors associated with the C-reactive protein concentrations. There was a significant correlation between IL-10 concentration and vegetation length. Conclusion: The inflammatory serum cytokines levels were elevated in IE in comparison to healthy controls. C-reactive protein concentrations correlated with cytokines levels. IL-1β and IL-12 serum concentrations were higher in staphylococcal when compared to streptococcal IE. IL-10 levels were associated with vegetation size.