In the context of constraint logic programming and theorem proving, the development of constraint solvers on algebraic domains and their combination is of prime interest. As an example, a constraint solver in nite algebras is presented for a constraint language including for instance equations, disequations and inequations. By extending techniques used for the combination of uni cation in disjoint equational theories, we show how to combine constraint solvers on di erent algebraic domains that may share some constant symbols. We illustrate this technique by combining the constraint solver in nite algebras with other uni cation algorithms, and with another constraint solver on a di erent nite algebra.