The rolling thin film oven (RTFO) test has been found to be inadequate for aging polymer-modified binders. A modified German rotating flask (MGRF) was evaluated as a replacement for the RTFO aging method. Evaluation involved three phases by using a wide range of asphalt binders, primarily polymer-modified asphalt binders. Phase I was conducted to evaluate the effects of temperature and rotation speed on aging. Phase II identified off-the-shelf components to facilitate the assembly of MGRF. A fully functional, off-the-shelf MGRF was developed at the completion of Phase II. The cost of this equipment was approximately $3,500. Phase III was conducted to evaluate the effects of the MGRF aging procedure on a wide range of asphalt binders. In Phase III, a full range of binder physical properties was determined to grade all binders according to AASHTO M320 and MP1-a. The MGRF aging procedure did not significantly affect the performance grade of the asphalt binders studied. Therefore, from the available data, MGRF aging appears to be equivalent to RTFO. The advantage of using the MGRF is that it does not have the run-out problems faced by the modified binders in an RTFO oven.