Date on the solubility of urea L-tartaric acid in aqueous ethanol solution are essential for industrial design and further theoretical studies. Using a laser monitoring system, the solubility of urea L-tartaric acid in aqueous ethanol solution at different temperatures was measured using the synthetic method. For the temperature range investigated, the solubilities of urea L-tartaric acid in the solvents increased with increasing temperature. The solubility data were correlated with Apelblat equation and Buchowski-Ksiazczak lambda h equation. The Apelblat equation can regress the solubility data much better than Buchowski-Ksiazczak lambda h equation. This study provides valuable data for the mechanism and preparation of the available crystal form of urea L-tartaric acid. (C) 2008 Elsevier B.V. All rights reserved.