This study aimed to investigate the effect of incubation and storage temperatures on quality of set yoghurt made from cow milk during storage life of 10 days. The yoghurt mix was prepared by adding 100 Kg skim milk powder to 341 liters of distilled water and then mixed for 20 minutes and adding 60 liters fresh cow milk. The yoghurt mix was pasteurized at 90^oC for 20 minutes and then cooled to 45^oC. A 2% of mixed starter culture type (CH-1, B-3) was added. Then it was incubated at different incubation temperatures (41^oC, 43^oC, 45^oC) for 4 hours. Physiochemical characteristics such as acidity, viscosity, wheying-off and sensory quality were carried out at zero time and after one day in order to select optimum incubation temperature. Then optimum sample was stored at two temperatures (6^oC and 10^oC) to study the effect on quality. The results showed that the incubation temperature of 45^oC gave the best quality yoghurt compared with incubation temperatures of 41^oC and 43^oC as measured with the parameters of acidity, wheying-off, viscosity and sensory quality. Storage temperature of 6^oC gave the better quality yoghurt compared with storage temperature of 10^oC which resulted in large amount of whey separated, low viscosity and low acidity.