Mild winter weather conditions reduce fruit yield and quality of many peach cultivars grown in the Medium Chill Region of the United States. Peach fruit shape instability limits marketing options for growers in this region. The Stonefruit Breeding Program at Texas A&M University evaluated a wide range of peach cultivars and breeder selections from throughout the world during the mild winters of 1988-198 9 and 1989-1990. Fruit shape response was highly variable among genotypes with similar chilling requirements. The implication of this is that the potential is high for eliminating fruit shape instability due to highly variable winter conditions in the Medium Chill Peach Production Region.