This paper presents the results to date of an ongoing study on the effects of temperature and mechanical fatigue on the residual strength of a five-harness satin weave reinforced polymeric composite. Unaged specimens underwent mechanical fatigue testing at room temperature and at 120°C. Tests were interrupted at two different stages of fatigue life to monitor damage and to obtain stiffness changes and residual strengths. Initial material strength and stiffness were measured to be approximately 738 MPa and 65.6 GPa, respectively, at both temperatures. As a result of fatigue loading (R = 0.1) at 455 MPa and 10 Hz, the strengths remained unchanged, but the residual stiffness decreased at both temperatures, particularly at 120°C. Data collected thus far show that temperature has a significant impact on fatigue life.