Mammalian cell culture has wide and expanding applications in both research and biotechnological/pharmaceutical industries The development and routine use of serum-free media (SFM) is a high priority for cell culture from both an industrial and scientific point of view as evidenced by the literature and the ever increasing supply of commercial preparations designed to bulk up growth in serum-free systems Production of vaccines, therapeutics and monoclonal antibodies for diagnostic and therapeutic purposes are just some of the many applications in which mammalian cell culture can dominate. For cell culture products to be of diagnostic and therapeutic use, the quahty o f these biomaterials need to meet the highest standards In addition to precise process control during isolation of the product, the milieu in which the cells are active is of prime importance. The complexity and undefined nature of serum has been recognised for some time Several approaches have been taken to deal with this, including reduction or total elimination of serum from the medium With the development of SFM, problems have been encountered Cell types exhibit different nutritional and supplemental requirements With the amount of variables in ever increasing combinations and numbers that can be used, the task of finding a SFM for a particular cell line is daunting. In this literature survey, the problems associated with the use of serum and the development of more defined culture conditions are discussed An overview of the factors generally used in the replacement of serum are presented The possible advantages of using serum-free medium on an industrial scale are investigated An outline of commercially avadable serum-free medium is given. A detaded review of three of the most commonly used factors in serum-free medium, insulin, transferrin and bovine serum albumin (BSA) is presented with a view to replacing these components with non-ammal-denved products m order to develop more defined media.