Abstract Ultrasonic wave properties (attenuation and velocity) in the particle compounded agarose gels have been experimentally studied in the range from 1 to 30 MHz. The particles used were talc, glass beads and graphite. The effects of size and volume concentration of particles were clearly observed as changes of ultrasonic wave properties. Applying the Urick's theory for viscous liquid suspensions, the specific curves of velocity in the gels were observed as a function of aβ, where a is the radius of the particles and β is described by angular frequency ω, density ρ and fluid viscosity η. This indicates that the particle behavior in the gels seems to be similar with that in the viscous fluid. The estimated η in the gels was higher than that of the free water, showing the high viscosity in the gels.