Using the nuclear magnetic resonance (NMR) pulsed field gradient (PFG) technique, it is possible to determine the size distribution of emulsion droplets. This method is extended so that the same measurements can be performed in the presence of flow. The resultant flow-compensating NMR-PFG technique is used to determine the oil droplet-size distribution of an oil-in-water emulsion flowing in a narrow tube at various flow rates. Comparison with the nonflowing oil droplet-size distribution enables the effect of velocity shear on the oil droplet-size distribution to be quantified.