Criteria to be followed in predicting new eutectic systems of particular types are discussed briefly, and demonstrated in the discovery of the Cd3As2-NiAs eutectic. The eutectic region of the Cd3As2-NiAs pseudobinary phase diagram has been determined by thermal and microscopic analysis. Cd3As2-NiAs eutectic ingots have been directionally grown by a new process, the liquid encapsulated Stockbarger technique, and shown to exhibit a typical rod-type morphology. © 1969 Chapman and Hall.