The U.S. Environmental Protection Agency is evaluating pollution reduction capabilities of vapor degreasers and new developments in vapor degreasing systems and operations. The principal objectives of this project are to develop and implement a program for assessing solvent loss from degreasing systems of various designs, and to report the test conditions, procedures, results, and conclusions in a form usable by air pollution agencies and industry. Tests were performed from October 1978 to July 1979 to evaluate the effects of different variables on the rate of solvent loss from degreasers. The variables tested include the following degreaser modifications and operating conditions: freeboard ratio, load cross-sectional area, refrigerated freeboard chiller, hoist speed, lip exhaust, crosscurrent air velocity, degreaser size, solvent type and lid. The cost of each modification was analyzed based on capital costs, annual expenses, and solvent saved because of the modification. The evaluations of solvent loss or savings were based only on the degreaser operating period; idle time (the solvent boiling and cooling period) was disregarded.