Waxy, that is, pure, amylopectin maize (Zea mays L.) is an important staple food and vegetable in Southeast and East Asia. Its insufficient protein quality could be remedied by the opaque-2 gene mutation, demanding the combination of two recessive endosperm quality genes, opaque-2 (o(2)o(2)) and waxy (wxwx). Crosses were made between waxy and opaque-2 maize as female and male parents, respectively. In the segregating progenies of two crosses, Kwi1 x AgQ53 and Kwi9 x AgQ53, immediate selfing or one-time backcrossing to the waxy parent before selfing were used to achieve the combination o(2)o(2) wxwx, supported by marker-assisted selection (MAS) of opaque-2 by phi057 and of waxy by phi022. The final 11 o(2)o(2) wxwx lines were achieved both from initial backcrossing and selfing. All the o(2)o(2) wxwx lines were of acceptable agronomic vigor and had very high percentages of amylopectin. The sugar content was mostly higher in both selfing and backcrossing lines than in the parental waxy lines, an advantage for vegetable marketing. High lysine and tryptophan contents of the o(2)o(2) wxwx lines prove that the goal of combining two quality traits within one grain was achieved. Furthermore, high variation in grain quality traits is an incentive for further improvement by breeding. Consumption of high-quality protein maize will improve the diets of children, a good reason to produce double-quality vegetable waxy maize.