Efficiency of in vitro methods for chromosome duplication in haploid melon is very low. This study was conducted to rind a new efficient in vivo method for chromosome duplication of haploid melon (Cucumis melo) plants. Tested techniques were (i) colchicine application to lateral buds by medicine dropper, (ii) by colchicine containing agar, (iii) by colchicine imbibed cotton and (iv) shoot tip immersing in colchicine solutions. After treatments, ploidy level of plants were determined morphologically (leaf and flower dimension, presence or absence of pollen) and measured by flow cytometry. The results showed that among the tested methods, "shoot tip immersing into colchicine solutions" was the most successful technique. Dihaplodization efficiency by shoot tip immersing was about % 91.67. Duplication rate was four times more than application by cotton, ten times more than application by agar. Colchicine treatment by medicine dropper was not found as an efficient technique for chromosome duplication.