A new "standard nonlinear solid" reduced relaxation function has been developed to describe the measured relaxation responses of tendons with 3% and 4% strain levels. This new reduced relaxation function has been used in modeling tendon responses with the quasi-linear viscoelastic law. Unlike the reduced relaxation functions employed in previous studies, the present function closely fits the measured relaxation responses for both the short term of the first few seconds and the long term of 22 hours. The relaxation responses of the anatomically paired tendons were found to be more alike than those from different sites.