The purpose of this study was to determine the inter- and intra-rater reliability of assessing upper limb postures of workers performing manufacturing tasks. Assessment of neck, shoulder, and wrist postures of 20 manufacturing employees was conducted by two raters observing digital video files using Multimedia Video Task Analysis (MVTA). Generalizability theory was used to estimate the inter- and intra-rater reliability. The results demonstrated good to excellent inter-rater reliability for neck and shoulder postures and fair to excellent inter-rater reliability for wrist postures. Intra-rater posture assessment demonstrated good to excellent reliability for both raters in all postures of the neck, shoulder, and wrist. This study demonstrated that posture assessment of manufacturing workers using MVTA is a reliable method.