Cold tolerance/resistance of 41 hazelnut hybrid strains was investigated by evaluating electrolyte seepage velocity, recovering growth, and tissue browning for the tested cold temperatures. Results demonstrated that electrolyte seepage velocity of all tested strains was faster as temperatures dropped down. The S curve relationship was found between seepage velocity and temperature. Turning point temperature used as the half deadly injured index (LT50) was developed using a logistic equation. The mean LT50 and temperature causing tissue browning were excellent indexes to predict cold tolerance/resistance. After treated at –30 or –35 °C and then evaluated for their recovering growth, 10 cold-resistant hybrid hazelnut strains were developed. These hybrids are being tested for regional adoption and will be released as commercial cultivars.