Reports indicate that exogenous gangliosides can accelerate neurite outgrowth in vitro and facilitate peripheral nerve regeneration in vivo. An experiment was designed to assess whether ganglioside administration alters functional recovery and neuronal regeneration after a CNS lesion. Rats trained on an alternation behavior and subjected to a unilateral entorhinal cortical lesion were given daily (i.m.) injections of either total brain ganglioside or GM1 ganglioside. Results show that ganglioside administration reduces the extent of behavioral deficit caused by the lesions and facilitated the course of functional recovery. It is hypothesized that gangliosides are enhancing hippocampal sprouting which occurs subsequent to the entorhinal lesion.