beta-Carbolines, such as methyl beta-carboline-3-carboxylate (beta-CCM), attach to the benzodiazepine receptors in the brain, but have effects completely opposite to those of benzodiazepines: beta-CCM is a convulsant at high doses, an anxiogenic at moderate doses, and enhances learning at low doses. The aim of this work was to detect some of the chromosomal segments involved in the regulation of beta-CCM-induced seizures. The method used was a derivation of the classical use of linkage-testing strains. We tested several strains and some of their intercrosses and back-crosses. For two of these strains, we obtained significant results showing that genes located on chromosomes 4 and 13, provisionally termed respectively Bis1 and Bis2, were involved in the regulation of beta-carboline-induced seizures. Testing of these two strains with two other convulsant agents (pentylenetetrazol, which acts at the picrotoxine site of the GABA receptor complex, and strychnine, which acts at the glycinergic receptor) provided evidence that the genes implicated are not involved in general seizure processes but specifically in beta-CCM-induced seizures.