The connections between two parts of the claustrum in the rat and rabbit were studied using the highly fluorescent lipophilic carbocyanine dye (Dil). After the application of Dil crystal into the endopiriform nucleus, labeled fibers in the insular claustrum were observed in its part directly neighboring the insular cortex and capsula externa. Additionally, numerous projections into the piriform, insular and entorhinal cortices were present. The presence of connections between the endopiriform nucleus and insular claustrum suggests its role concerned with the processes taking part in the allocortical regions as well as in the limbic system.