A field experiment was carried out at the experimental farm, faculty of Agriculture and Natural Resources,Aswan University during2018-19 and 2019-20 seasons to identify the suitable planting date and the optimum plant density on growth, yield and its quality of quinoa cv.Regalona under sandy soil using drip irrigation system.The experiment was carried out in(RCBD)using split-plot plot design with three replications, where planting dates (P₁: 10^thOctober, P₂: 25^thOctober and P₃: 10^thNovember)were occupied main plots and plant density (D₁:56.000, D₂:70.000 and D₃:84.000 plant fed^-1)were arranged sub-plots. Results revealed that planting quinoa on 10^th October resulted in maximum plant height, number of inflorescence plant^-1, 1000-seed weight, seed yield fed^-1and chemical compositions in both seasons.The delay of sowing led to increased carbohydrate concentration in seeds. The impact of plant density was significant for all studied traits in both seasons. Seed yield increased by(39.83 and 50.38%)with increase of plant density from 56.000 to 84.000 plant fed^-1 in the 1^st and 2^nd seasons, respectively. The increase of plant density significantly decreased both weight of 1000-seed and protein percentage in both seasons. Interaction between sowing date and plant density(D×P)showed that the highest seed yield fed^-1obtained in the 1^st date(10-October)with density84.000 plant fed^-1(753.60 and 767.93 kg fed^-1)in both seasons. The highest seed protein content resulted from sowing at 10-October with density56.000plant fed^-1.Ultimately, it can be concluded that planting quinoa(cv. Regalona)on 10^thOctober with sowing density 84 thousand plant fed^-1 could be recommend to maximize quinoa productivity and its quality of seeds under the climatic condition prevailing of Aswan Governorate