The objectives of this study were (1) to compare great cardiac vein (GCV) flow velocity detected by pulsed Doppler echocardiography (PDE) with Doppler guide wire (DGW) in the experimental setting and (2) to clarify whether transthoracic Doppler echocardiography (TTDE) can detect GCV flow in humans. Using opened-chest dogs, we detected GCV flow by PDE under the guidance of color flow Doppler mapping. GCV flow velocity was recorded by PDE and DGW, simultaneously. In 23 volunteers, GCV flow velocity was measured by TTDE. In the experimental setting, the prominent systolic flow wave of the GCV was obtained in PDE and DGW. There were good agreements between PDE and DGW for the measurements of GCV flow velocity (peak velocity: r = 0.98, y = 1.12chi-5.9; time velocity integral: r = 0.97, y = 1.10chi-0.71). In the human subjects, clear envelopes of GCV flow velocity were obtained in 21 (91%) of 23 subjects with the use of TTDE.