Effects of process parameters such as forming temperature, forming air pressure and heating time on wall thickness distribution in plug-assist thermoformed food containers using multilayered material were investigated. Multilayered rollstock-base material formed into containers by thermoforming process using a Benco aseptic packaging machine. Forming temperatures in the range of 131-170 degrees C, air-forming pressures of 2, 3, 3, 5 and 4 bars, and heating times of 66, 74, 84, 97 and 114 seconds were used in the thermoforming process. Analysis of wall thickness data obtained for the thermoforming parameters used in this study showed that wall thickness was significantly affected by forming temperature, pressure and heating time at 0.05 significance level. Besides the processing parameters, wall location, container side, and their interactions significantly affected wall thickness. Forming temperature was found to be the principle parameter influencing wall thickness distribution in a plug-assist thermoforming operation. The optimum operating conditions of the packaging machine for the thermoforming process are: 146-156 degrees C for forming temperature, 2-4 bars for air-forming pressure and 74-97 seconds for heating time.