Laser beam welds are usually symmetric. They can form asymmetric weld seams by introducing ultrasound, which normally can be used for grain refinement and reducing segregation. The investigations comprise ultrasonic assisted laser beam welding around antinode position of a stationary ultrasonic wave. The experiments are carried out with 2.4856 round bars, a laser beam power of 6 kW, a welding speed of 0.95 m/min and ultrasonic amplitudes of 0 µm and 4 µm. The welding positions are placed 0/7.5/15.0 mm on the right and left side of antinode position. Afterwards, specimen macrographs and micrographs of metallographic cross sections are made. As a result, the direction dependent asymmetry of the weld seams due to the position in the vibration distribution was proved. In addition, two different approaches are described to explain the fluid dynamic processes.