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Cardiogenic motion of the right lung parenchyma (CGLM) was measured in six morphine-pentobarbital-anesthetized dogs (11-16 kg) under conditions of varying paced and spontaneous sinus heart rates. Motion of 1-mm-diameter percutaneously implanted radiopaque lung parenchymal markers were measured using a computer-based biplane video-roentgenographic assembly. Correlation of the amplitudes and phases of marker motions to the R wave of the electrocardiogram (ECG) were determined utilizing a modified fast Fourier transform algorithm. Of initial importance was the observation that CGLM was significantly greater than the variability of repeated measurements. The total amplitudes of motion of the markers (where AT = square root A2X + A2Y + A2Z and AX, AY, AZ are the amplitudes of marker motion along the orthogonal X, Y, and Z body axes) in the right apical, cardiac, and diaphragmatic lobes were 0.025 +/- 0.005 (SE), 0.046 +/- 0.005, and 0.023 +/- 0.025 cm, respectively, (P less than 0.01, cardiac lobe vs. others). The total amplitude of motion observed in the cardiac lobe was equivalent to earlier observations of total amplitude (0.045 +/- 0.004 cm) of marker motion in response to high frequency airway oscillation at a pump stroke volume of 22-26 ml. An analysis of the higher harmonics of marker oscillation suggested that the second harmonic of CGLM is also larger than the variability of our measurements.