To choose the best vaccine from the available vaccines is a difficult task for the veterinary practitioner. The aim of this article is to tender the practitioner criteria for making the best choice. Efficacy is the most important criterion when selecting a vaccine. The efficacy can be assessed by studying the results of well-designed vaccination-challenge experiments performed in the laboratory and of field trials. Safety is the second criterion for quality of vaccines. Other aspects that can influence the choice of a vaccine are: available documentation, the cost and biopharmaceutical data. A systematic and objective comparison of the quality criteria of vaccines will lead to the selection of the best vaccine.