The axial and radial distributions of solid and gas holdups were investigated in an air-water-glass bead circulating fluidized bed (GLSCFB) using a new ultrasonic technique, with a new method based on signal fluctuations. The cross-sectional averaged gas and solid holdups measured at two axial positions appear to be similar at all studied operating conditions. The radial non-uniformity decreases with increasing liquid velocity but does not change with an increasing solid circulating rate. The radial distribution of gas holdup was more uniform for 1.3 mm beads than for 433 mum glass beads.