Starting from the Taylor equation [Taylor, G. I., Proc. R. Sec. London Ser., A 138, 41-48 (1932)] for the viscosity of very dilute emulsions, new viscosity equations are developed for concentrated emulsions using the effective medium approach. According to the equations derived in the paper, the viscosity of concentrated emulsions increases with the increases in the volume fraction of the dispersed phase and the viscosity ratio (K) of the dispersed phase to the continuous phase. In the limit of K --> co, the equations reduce to the well-known formulas for solids-in-liquid suspensions. The proposed equations are evaluated in light of a large body of experimental data for concentrated emulsions, covering a broad range of dispersed-phase to continuous-phase viscosity ratio (3.87 x 10(-4) less than or equal to K less than or equal to 3.25 x 10(5)). (C) 2001 The Society of Rheology.