The prediction of two-phase pressure drops is important in the design of fluidized beds, heat exchangers, slurry transport lines, annular risers in reactors, driers, and other applications of particulate flows. Experimental data for liquid-solid up-flows through annuli are very limited. In this study, a correlation was developed for predicting two-phase pressure drops via Euler number (Eutp) for liquid-solid suspension up-flows in the fully developed flow region of an annulus in terms of mixture Reynolds number (Rem), solid particle Froude number (Frp), ratio of particle diameter to hydraulic diameter, and ratio of area-averaged solids density in the tested cross-sectional flow area of the annulus to the average density of the feed slurry entering the annulus. The proposed correlation, having an accuracy of almost 25%, was obtained for water-feldspar dilute suspension up-flows in an annulus with a hydraulic diameter of 79.8mm and with feldspar particles (2400kg/m3 in material density and 0.072-0.138 mm in average diameter) at low concentrations.