The purpose of the present paper was to look for genes that might be involved in anxiety-related behaviours by undertaking a genetic analysis of a simple mouse model of stress responsiveness. Two inbred mouse strains have been identified that show either high or low stress responsiveness. These strains were crossed to generate F1 progeny, which were then crossed to generate F2 progeny, and in which there is segregation of genotype within individual animals. DNA was isolated from these animals and a genome scan was conducted in order to find regions on the genome that correlate with the stress responsiveness. Several regions on the mouse genome show significant linkage with the stress phenotype. One region in particular, on chromosome 12, was further characterised and the most significant linkage was found between 32.8 and 44.8 cM. These chromosomal regions may contain genes encoding proteins that are involved in the underlying neural circuitry involved in stress responsiveness.