It is well known that glutamate receptors have significant role in the pain transmission. The activation of N-methyl-D-aspartate receptors causes persistent pain, therefore the antagonists acting on these receptors cause antinociception in chronic pain states. As the synthetic N-methyl-D-aspartate receptor antagonists have several side effects, they are not used generally in the clinical therapy. The tryptophan metabolite kynurenic acid is an endogenous antagonist of N-methyl-D-aspartate receptors. Although some data proved its neuroprotective effect, only a few studies suggest the antinociceptive potential of kynurenic acid. The goal of this review to summarise the possible role of kynurenic acid in the pain therapy based on the results of animal studies. Data available concerning this subject demonstrated that kynurenic acid is not an appropriate agent for antinociception neither in single nor in continuous administration because of its side-effect resulting in motor deficiency. On the other hand the combination of low doses of kynurenic acid and endomorphin-1 provides effective antinociception without side-effects on inflammatory pain test, thus may offer a new treatment modality in human pain therapy.