The present investigation was planned to optimize the inoculum concentration, setting temperature and sugar concentration for preparation of cow milk yoghurt on the basis of its physico-chemical and sensorial quality attributes. Inoculum (containing Streptococcus salivarius subsp. thermophillus and Lactobacillus delbrueckii spp. bulgaricus in 1:1 ratio) were added of sugar at different rates viz. 1, 2, 3 and 4 per cent with sugar concentrations of 8, 10, 12 and 14 per cent for three different setting temperature range (37, 42 and 45oC) and effect of these parameters on setting time, synersis, physico-chemical properties and organoleptic quality characteristics were investigated. The results revealed that optimum conditions for preparing cow milk yoghurt include sugar addition up to 12 per cent with inoculum level of 3 per cent at the temperature of 42oC which resulted in 6.2 per cent syneresis with the setting time of 7.2 hours.