【Objective】 To study the intracellular calcium concentration ([Ca]i) mobilized by heroin and the possible remedy by verapamil in newborn rat cardiomyocytes. 【Methods】 [Ca]i was measured with fluorescent intensity (FI) by confocal microscope in single cultured 5d newborn rat cardiomyocytes loaded with Fluo 3-AM; propidium iodide was added to identify dead cells.【Results】 The average fluorescence intensity and amplitude of calcium transients over 80 s recording period were statistically up-regulated by 0.01 mol/L heroin (P < 0.01). The effects were reversed by the addition of 20 μmol/L verapamil. Post-treatments with verapamil partly rescued the cell death induced by continuous administration of heroin. 【Conclusion】 Verapamil possesses the antagonistic effects and protective effects on the increased level and vibration of [Ca]i induced by heroin in cultured cardiomyocytes.