Concern about the atmospheric ozone has been crystallized in the Montreal Protocol that provides for the phased reduction of ozone depleting chemicals from the marketplace. The introduction of alternative fluids for various applications must be preceded by a significant amount of research and testing. The testing required includes both laboratory and system work. One of the challenges faced in this adjustment period is to define anew how laboratory data are to be used in conjunction with system test data in order to make judgments about the reliability and performance of proposed new systems. This paper presents some laboratory data that may be needed in this effort. The compatibility of R-134a with a class of lubricants is discussed. Further, the compatibility of the refrigerant/lubricant mixture with elastomers and other materials of construction is discussed. Some other properties such as solubility, load and wear characteristics are also discussed.