Ceramide, a sphingolipid metabolite produced by activation of sphingomyelinase, has been previously shown to reduce L-type Ca²⁺ channel current (I_Ca,L) in adult rat ventricular myocytes; however, its effect on contractile function is unknown. In this study, we investigated effects of ceramide on excitation-contraction coupling in adult ventricular myocytes and on left ventricular (LV) function in isolated hearts. Surprisingly, in patch-clamped myocytes, ceramide increased contraction concomitant with reductions in I_Ca,L. In intact myocytes, ceramide increased cell shortening (CS) concurrently with enhancing maximum rates of shortening and relaxation, and the duration of contraction. Ceramide also increased the amplitudes of post-rest potentiated (PRP) contraction. In Fura-PE3-loaded myocytes, ceramide increased systolic Ca²⁺, and the magnitude and maximum rates of the rising and declining phases of Ca²⁺ transients. Ceramide-elicited decreases in magnitudes of PRP relative to steady-state contraction and Ca²⁺ transient suggest an increased fractional Ca²⁺ release from SR. However, ceramide slightly reduced the caffeine-induced Ca²⁺ transient and had no significant effect on the amplitude of PRP-elicited Ca²⁺ transient. Additionally, ceramide-induced upward shift in the relationship of contraction and Ca²⁺ transient and increase in the Ca²⁺ responsiveness of CS suggest an increase in myofilament Ca²⁺ sensitivity. In isolated hearts, ceramide increased LV developed pressure and maximum rates of contraction and relaxation at balloon volumes of 30-50 µl. In some myocytes, ceramide induced arrhythmias in a pattern consistent with early aftercontractions. In summary, regardless of decreasing I_Ca,L, ceramide elicits distinct positive inotropic and lusitropic effects, resulting probably from enhanced SR Ca²⁺ release and uptake, and increased Ca²⁺ sensitivity of ventricular myocytes.