Consideration of alternative methods for animal tests in developing countries is important because good quality laboratory animals and proper animal facilities are not always sufficiently available to perform the currently required quality control tests. In vitro methods have been implemented at the National Institute of Vaccines and Biological Substances (IVAC) in Vietnam. These include serological tests (such as the Toxin Binding Inhibition test and the VERO Cell test) for the estimation of potency of Tetanus and Diphtheria toxoid vaccines and for the evaluation of vaccine field trials. Currently, an inhibition ELISA test to determine anti-rabies activity in equine rabies immunoglobulin preparations is being developed with the long-term goal of its introduction in Vietnam. The results from validation studies are promising and have contributed to decisions made by the National Control Authority to replace imported DPT vaccines in the EPI program with Vietnamese-produced DPT vaccines. This paper summarizes IVAC's experience in introducing alternatives in Vietnam over the last 10 years and reports on the various local validation studies which were performed during this period.