In this paper, flow pattern and aerodynamic performance of vortex blowers with 3-dimensional blade form are studied. It is shown that the velocity within the casing increases with decreasing blade angle. Pressure and power coefficients are about two times as large as those of the 2-dimensional vortex blower. Results indicate that the peripheral direction velocity values at the blade inlet and blade outlet in the vortex blower are large, and the flow revolues passes several times between the inlet and outlet of the casing. The pressure and power coefficients are strongly related to the outlet blade angle the inlet blade angle, the number of blades and the ratio of the inlet diameter to the outlet diameter. The pressure coefficient is increased three fold as the outlet blade angle is decreased from 90 degrees (2-dimensional) to 70 degrees (3-dimensional), and is also increased by 20% as the inlet blade angle is decreased from 70 degrees to 40 degrees.