Poor reproducibility in the determination of low temperature properties of rubber has been investigated. The level of variability for three acrylonitrile rubber compounds in interlaboratory tests are quoted. The design of new equipment to overcome these difficulties using a simple dynamic test system is described. This incorporates a frictionless measurement system and allows for the determination of stress during a number of cycles of sinusoidal deformation at adjustable low frequencies. Tests are made on strips of rubber in tension and can allow for different levels of prestrain. To avoid errors due to bowing of the test strip a sliding lower grip is used. The effects of type of grip, intermittent and continuous oscillation, prestrain level, specimen size, test frequency, and rising or falling temperature have been investigated. Tests have covered a selection of different rubbers, and extensive evaluation of reproducibility has been carried out on nitrile rubbers of different plasticizer levels.