The minimum speed required for complete suspension (N-js) is a major parameter for solids suspension in stirred tanks. Micale et al. 7th UK Conference on Mixing (2002) determined N-js by using a pressure gauge technique in a model vessel. In the present work N-js was measured by the same later technique in a more practical vessel with varying C/T ratio and the impeller direction of rotation. The results were compared to those obtained by Zwietering Chem. Eng. Sci. 8, 244-253, (1958) correlation. Agreement was found between results from present work and predictions by Zwietering's correlation with maximum difference not exceeding 17%.