Experiments were carried out in monodisperse suspensions at which particles consisting of uniform suspension, caused to fall down counter-currently against an upflow of water in a vertical tube. The solid concentration was measured to determine particle velocity. The total solid concentration ranged from 5% to 45% by volume. A correction factor of (voidage)(0.2) applied to the model of Garside and Al-Dibouni (1977), gives satisfactory results for reduced velocity at intermediate particle Reynolds number. The data obtained for monodisperse suspensions were tested against the published models. The modified model gives a mean sum of squares of residuals 0.0004 as well as better results than the other models in the flow range 150 < Re < 2200.