This study aimed to determine, using single factor experiments and orthogonal array design, an optimal roselle-supplemented yoghurt formulation when a stabilizer composed of gellan gum, agar and locust bean gum was used. It was shown that the best thickener concentrations were 0.04, 0.04 and 0.02 g/100 g for gellan gum, agar and locust bean gum, respectively. The best concentrations of roselle powder, stabilizer and sugar were 0.3, 0.6 and 8.0 g/100 g, respectively. Roselle powder was suspended in distilled water, adjusted to pH 5.5 in order to protect the stability of red pigments from roselle, and then added to the raw milk before fermentation.