Ultrasonic compressional (V,) and shear (V,) velocities were measured on 69 sandstone samples, at dried and watersaturated states under external confining pressure up to 50 MPa and internal pore pressure 1 MPa. Porosities of the samples ranged from 5 to 30 percent and volume clay content of the samples ranged from 0 to 50 percent. These velocity data were treated to estimate velocity dispersion on saturated sandstones with frequencies from 1 MHz to 1 Hz using the Biot-Gassmann theory proposed by Winkler (1985, 1986). Biot velocity dispersions (BVD) were defined as differences between the highand the low-frequency (say 1 Hz) limits calculated from the Biot theory. Apparent velocity dispersions (AVD) were defined ss discrepancies between the ultrasonic saturated velocity and the low-frequency limit of the Biot theory. Both BVD and AVD are normalized by ultrasonic water-saturated velocity. In our samples, the BVD are about 1 percent or less, increasing with increasing porosity and effective stress, and decreasing with increasing clay content. For well cemented sandstones, especially clean sandstones, the AVD agree well with the BVD, which is similar to dispersion behavior of fused glass beads noted by Winkler (1985). For poorly cemented shaly sandstones, the AVD (4 to 9 percent) are much greater than the BVD. This suggests presence of some non-Biot absorption/dispersion mechanisms. The non-Biot velocity dispersions (NBVD) appear to decrease with increasing porosity and effective stress, and increase with increasing clay content. The effects of porosity, clay content and effective stress are all suppressed by increasing grain cement, contact and compaction.