The laminar flow over a prolate spheroid was investigated via flow visualization and Laser-Doppler Velocimetry. Experiments were conducted in a water tunnel and the flow was visualized with dyes. The measurement of three-dimensional boundary layers required a special design of the laser optics. Attention was focused in the neighborhood of three-dimensional separation. The Vortex-Lattice method was employed to calculate the inviscid flow and the development of separated vortex sheets over a prolate spheroid. An approximate-method based on the assumption of local similarity was used to solve the boundary layer equations and calculate the line of open separation. A condition of vortex shedding along separation is proposed. The two schemes, viscous and inviscid, interact through the line of separation which is allowed to displace as the wake grows. Results are compared with flow visualization data for laminar separation and pressure data for turbulent separation. / Ph. D.