Watermelon (Citrullus lanatus Thumb. Matsum. and Nakai) flower petals usually are yellow, but in watermelon line Kw-695, light-green flowers were detected. To study the inheritance of light-green flower color, Kw-695 plants were crossed with yellow-flowered Korean cultures `SS-4' and `Dalgona'. The resulting F1, F2, and reciprocal backcross generations were analyzed for flower color. Segregation ratios in the F2 and backcross to Kw-695 were 3 yellow: 1 light green and 1 yellow: 1 light green, respectively. Backcross generations to the yellow-flowered parents showed yellow flowers only. These results indicate that inheritance of the light-green flower character in Kw-695 is governed by a single recessive gene. We propose the gf gene symbol for the green flower trait. Kw-695 plants have large vines with large, light-green leaves. The plants are andromonoecious, have large, oval, bright yellow-green fruit with irregular dark-green stripes, bright yellow-orange, inedible flesh with very low sugar content (about 3.2 °Brix), and light-yellow seeds. The trait should be useful as a marker in watermelon breeding programs. Linkages between this trait and other genetic markers in watermelon will be investigated.