Abstract: A nursing bottle assembly includes a bottle having a closed end and an open end with a nipple being disposed over the open end. A flexible bag within the bottle has an open end secured to the open end of the bottle. The flexible bag which has its lower end disposed within the bottle is adapted to receive the liquid to be dispensed. Biasing means are provided to create a biasing force on the flexible bag to maintain a positive pressure on the liquid in the flexible bag as the liquid is dispensed through the nipple.