One hour before a contusive spinal cord injury either compound MK-801 or compound U-50488H was injected intraperitoneally, and a 14-day-delivery osmotic minipump containing the same drug was placed subcutaneously at the time of surgery. The motor and sensory behavior of the animals was measured over the following 30 days. Both MK-801 and U-50488H treatments had a statistically significant neuroprotective effect. The number of neurons per unit area outside the lesion epicenter was significantly (P less than 0.01) greater in the drug-treated animals (MK-801, 298.9 +/- 74.8 neurons/mm2; U-50488H, 242.7 +/- 16.5 neurons/mm2) than in untreated controls (73.3 +/- 9.3 neurons/mm2). Recovery of sensory and motor behavior was limited but significant differences were observed when drug-treated rats were compared with untreated controls. The effects of the two drugs were not additive for any of the variables studied.