Four inbred strains of mice, BALB/cByJ, C3H/2Ibg, C57BL/6Ibg, and DBA/2Ibg, were tested for their learning ability in the Morris water maze. Two forms of learning were examined: cue learning, in which the mice were required to swim toward a submerged platform marked by a proximal visual cue; and place learning, in which the animals were required to use distal visual cues to find a submerged platform. C3H and BALB mice, which lack good visual acuity, were incapable of either form of learning. Both C57 and DBA mice were capable of cue learning, but DBA mice performed poorly at the place learning task. A selective impairment in place learning is typical of rats with disrupted hippocampal function. A similar impairment in DBA mice may indicate that abnormal hippocampal function exists under baseline conditions in this strain.