Thermoplastic polyesters are the materials of choice in a wide variety of applications, including automotive electronics, due to their excellent balance of cost versus performance and their case of use in complicated designs. As with any material, thermoplastic polyesters do have limitations. Typical polyesters are susceptible to hydrolysis - the breaking of bonds within the polymer chain by water molecules, under certain environmental conditions such as a combination of high temperature and humidity. Upon hydrolysis, the mechanical properties of a typical polyester suffer significant deterioration due to a decrease in molecular weight.Recent standardization efforts within the automotive industry, under the USCAR banner, have highlighted the need for thermoplastic polyesters that can withstand aggressive temperature and humidity cycling. One company has recently developed a new technology that controls hydrolysis and significantly extends the performance of thermoplastic polyesters. The new hydrolysis-resistant polyesters are cost-effective materials for those applications which must survive the Class III and IV USCAR exposures. This paper will detail the performance and chemistry of the new hydrolysis-resistant polyesters and review their applications within the connector industry.