In a field experiment, F1 progenies betweenAndigenas partially adapted to long days and aTuberosum variety outyielded F1 progenies betweenTuberosum varieties by, on average, 13%. ATuberosum progeny which involved the Continental parentAckersegen outyielded others involving only British parents.Andigena Tuberosum progenies outyielded the BritishTuberosum progenies on average by 19%, the best hybrid progeny being 49% superior to them. Tuber sizes and earliness of maturity were, on average, closely similar inAndigena Tuberosum andTuberosum Tuberosum progenies, though the range of progeny-means was greater inAndigena Tuberosum. Lower-yieldingAndigena Tuberosum progenies were early-maturing, though not all early-maturing progenies were low yielding. Blight resistance was detected in fourAndigena Tuberosum progenies. It is concluded that pre-selection amongAndigenas for desirable characters may enable high-yielding commercially-acceptable varieties to be obtained from the F1 generation ofAndigena Tuberosum hybrids.