The Orr‐Sommerfeld equation is solved numerically for the boundary layer profiles which are the solutions to Stewartson's branch of the Falkner‐Skan equation. These profiles are of significance in describing post‐separation flows with negative skin friction. The cases considered are for the Hartree pressure gradient parameter&bgr; = −0.18, −0.15, −0.10, and −0.05. The profiles become more stable as&bgr;decreases from ‐0.05 to ‐0.18 in contrast to the results of the Falkner‐Skan similarity profiles with positive skin friction.