The microencapsulation of recombinant cells, widely used for in vitro high-density cell culture, is a novel and potentially cost-effective method of in vivo heterologous protein delivery, where the protein producing cells are immunologically protected from tissue rejection. We report here a simple, reliable and inexpensive laboratory method to generate calcium alginate microcapsules containing genetically engineered, interleukin-2 expressing, Chinese hamster ovary (CHO) cells.