A materials testing system was designed and constructed to perform cyclic-strain resistivity testing in magnetic fields to 8 Tesla and at temperatures from 4.2 K to 77 K. The system has a load capacity of 8.9 kN (2000 lb). Helium gas cooling is used to maintain a constant temperature in the 15 K to 50 K region. Data acquisition, including stress-strain information and resistivity measurements, is controlled by a personal computer. An overall helium consumption rate of 8 1/hr is achieved for a 20 K test in magnetic fields to 8 Tesla.