The objective of this study was to determine the effect of breed line and age on pH in broiler chicken breast muscles. pH valuesof m. pectoralis major muscle were compared within 6 groups - each line (Cobb, Ross, Hubbard) was divided into two groups aged 42 and 50 days. pH values were recorded 15 minutes, 24 and 48 hours after slaughtering. Older broilers showed significantly lower pH than younger ones. Interactions between breed line and age were found, except for pH after 24 hours. Meat quality of broilers can be estimated quickly by determining the pH-value of breast meat.