Abstract— The reorientational motions of the D96N and T46V/D96N mutants of bacteriorhodopsin in purple membrane have been investigated by time-resolved linear dichroism measurements. The reorientations in the early stages of the photocycle are identical to those observed in wild-type bacteriorhodopsin: anisotropics of photocycle intermediates in both D96N and T46V/D96N are rK= 0.38±0.01, rL= 0.35±0.01, rM= 0.35±0.01. The anisotropy of the initial state, rBR, exhibits decays to zero in D96N and to negative values in T46V/D96N on the time scale of tens of milliseconds. This anisotropy decay can be explained by a model that involves the motion of unexcited or spectator proteins adjacent to a photocycling protein. The amplitude and time constants of spectator reorientational motion are similar to those that have been observed in the wild type. Contributions from the anisotropy of the N-state were detected in measurements of the T46V/D96N mutant, in which a large N-state population accumulates. The value of rN is estimated to be 0.30±0.05 in T46V/D96N.