An ultrasonic interferometer technique for measuring the temperature dependence of relative changes in elastic constants has been utilized to study the variation ofc11for germanium. Results are reported for measurements carried out as a function of frequency from 30 Mc/sec to 170 Mc/sec for compressional wave propagation along the [100] direction in two sets of compatible germanium samples over the temperature range from −60°C to 0°C. The mean value of (1/c11) (dc11/dT) is 78.87×10−6(°C)−1, and no systematic frequency dependence of (1/c11) (dc11/dT) was found.