The Ultra-high-temperature (UHT) processing and aseptic packaging of fluid milk products greatly extends product shelf life. This technology has been used in Europe for many years but has been introduced only recently into the United States. The economic feasibility of UHT products depend in part on processing costs. This study specifies four model UHT processing plants and develops engineering cost estimates for these plants. The costs of UHT processing are compared with conventional pasteurization costs.