This paper presents a formal model, namely Biometric Privacy–Security–Trust Model (BioPSTM), aiming to describe the tradeoff between privacy and security and their relationship with trust in biometric authentication systems. The relationship between trust and privacy–security pair requires a comprehensive approach that should consider user acceptance and the pricing between privacy and security. The proposed model is quite new in that it combines the formal formulation of tradeoff between privacy and security with trust over a user's acceptance model. The formal model presents a three-dimensional approach to indicate demand responsive pricing between privacy, security, and trust. The model is interpreted over a general syndrome-based biometric template protection method by discussing possible privacy and security requirements. The proposed model has been applied on countries that are aware of biometric security technologies. The evaluation on country profiles presents an overall description of the user acceptance model and its relationship with biometric technologies. Copyright © 2012 John Wiley & Sons, Ltd.