AIM: To investigate the effect of Ginkgolide B (GB) on action potential (AP), delayed rectifier potassium current (IK), and L-type calcium current (ICa-L) in guinea pig ventricular myocytes. METHODS: Single ventricular myocytes were isolated by an enzymatic dissociation method. AP, IK, ICa-L were recorded by whole-cell patch-clamp technique in either current or voltage clamp mode. RESULTS: GB shortened APD in a concentration-dependent manner. GB 0.1, 1, and 10 μmol/L shortened APD50 by 7.9 % (n=5, P＞0.05), 18.4 % (n=5, P＜0.01), and 28.9 % (n=6, P＜0.01), respectively; APD90 by 12.4 % (n=5, P＞0.05), 17.6 % (n=5, P＜0.01), 26.4 % (n=5, P＜0.01),respectively. GB increased IK in a concentration-dependent manner. GB 0.1, 1, and l0 μmol/L increased IK by 20.1% (n=6, P＜0.05), 43.1% (n=6, P＜0.01), 55.6 % (n=6, P＜0.05); increased IKtail by 10.7 % (n=6, P＜0.05),25.1% (n=6, P＜0.05), and 37.7 % (n=6, P＜0.05), respectively at testing potential of +50 mV and shift the I-V curve of Ik upward. But GB had no significant effect on ICa-L at above concentrations. CONCLUSION: GB significantly shortened APD in a concentration-dependent manner which mainly due to increase of IK.