When a strut or other object is attached to a surface along which a fluid flows, the strut disturbs the boundary-layer flow and the wake region of the strut interacts with the boundary layer along the surface giving rise to complicated three-dimensional effects. In the present paper these effects were investigated for a geometry consisting of a 2-in-diam cylinder in uniform axial flow to which was attached normally a 3/16-in-diam dowel forming a strut. The measurements reported include both static and total-pressure surveys in the wake-boundary layer region behind the strut. The resulting wake velocity profiles far from the interaction region behave normally but those within this region do not. The existence of vortexes is in some cases clearly seen.