The quantum Smoluchowski equation is an equation for the coordinate-diagona
l elements of the density operator, and it is identical to the classical Sm
oluchowski equation. Here, the leading finite-friction correction to the qu
antum Smoluchowski equation is derived, for the particular case of the over
damped harmonic oscillator. It is in fact a quantum correction, different f
rom the well-known classical correction, and it dominates the classical cor
rection in the strong friction regime.