We have previously reported that selective axotomy of serotoninergic neurons produced by an intraventricular injection of 5, 7‐dihydroxytryptamine is followed by an increase in 5‐HT1B binding sites in the suprachiasmatic nucleus of the hypothalamus. This post‐lesion up‐regulation is shown here to be spontaneously reversed after long‐term survival in spite of an incomplete reinnervation of the nucleus. Recovery may be accelerated by fetal raphe transplants that produce more rapid reinnervation.