The effects of the NMDA/glycine site antagonist, 7-chloro-4-hydroxy-3-(3-phenoxy)phenyl-2(1H)-quinolone (L-701,324), and the benzodiazepine receptor agonist, diazepam, were examined in the elevated plus-maze and in the Vogel's conflict test. Oral administration of L-701,324 caused a dose-dependent increase (2.5 and 5.0 mg/kg, -30 min) in the percent time spent in the open arms with no change in the total number of arm entries or in the percent entries into the open arms of the plus-maze. The same doses of L-701,324 increased punished responding in the Vogel's conflict test in a dose-dependent fashion, with no influence on unpunished drinking behavior. The anxiolytic-like effects of L-701,324 were obtained at doses which by themselves had no influence on the locomotor activity of the animals. Diazepam (2 mg/kg, i.p., -30 min) was slightly more effective than L-701,324 in the plus-maze situation, whereas the increase in punished drinking in the Vogel's test was of the same magnitude for both compounds. Our present results suggest that inhibition of NMDA receptor activity via a blockade of the NMDA/glycine-sensitive site at the NMDA receptor is accompanied by a reduction of anxiety-like behavior in both non-conditioned and conditioned conflict behavior situations.