The goal of the present study was to examine the musculophrenic vein of 29 healthy Swiss Braunvieh cows using colour-Doppler sonography to determine vessel morphology and diameter, and blood flow velocity. The hair over the reticular region was clipped, and the left musculophrenic vein was examined before and 10min after sedation using 0.03mg/kg xylazine. The musculophrenic vein appeared as a vessel with a diameter of 0.5-1.1cm located in the diaphragmatic musculature. The spectral display was a broad band structure with a wave-like shape. The Doppler measurement point was 1.5-2.7cm from the body surface. The diameter of the vein and the blood flow velocity did not differ significantly before and after sedation. Before sedation, the mean diameter (+/-SD) of the musculophrenic vein was 0.7 (0.2) cm, the maximum blood flow velocity 90.2 (38.6) cm/s, the mean blood flow velocity 60.4 (22.3) cm/s and the minimum blood flow velocity 41.4 (24.2) cm/s. There were significant correlations (r=0.45-0.90) between blood flow velocity before and after sedation and between minimum, maximum and mean blood flow velocities.