This paper is concerning the performance evaluation of small size thermal vapour compression (TVC) desalination units. The plant consists of two identical vapour compression units, each of a nominal capacity of 375 m(3)/d of distillate water. Despite the fact that these units are fairly new (two years in operation at time of evaluation), some operating problems were experienced. In this study, some important design factors and operating conditions are reviewed and the plant operating data were used to evaluate the unit performance. Conclusions derived from this evaluation are presented with emphasis on plant economy.