Approach-avoidance tendencies play a major role in the development and maintenance of anxiety disorders as repeated avoidance behaviours are assumed to prevent fear extinction. Avoidance decisions and their effect on fear extinction were investigated in two separate studies with varying avoidance costs. In both studies, a Virtual Reality fear conditioning procedure with ecologically relevant avoidance costs (temporal delay and physical effort) was employed. Participants had to choose between a safe stimulus (low reward, no unconditioned stimulus (US)) and a risky stimulus (high reward, 75% chance of encountering the US). After differential fear acquisition and learning to prevent the US using a virtual avoidance button (avoidance learning), participants were randomized to an Avoidance condition or No Avoidance condition during fear extinction. Results showed high (Study 1), but not low (Study 2), avoidance costs resulted in less avoidance behaviour. Even though there were no between-group differences, comparing avoiders and non-avoiders in both studies demonstrated that avoidance behaviours protected acquired fear from extinction, resulting in the maintenance of US-expectancies and a sustained preference for the safe stimulus. These results provide insight in how avoidance behaviours maintain fear responses and how treatment might be improved by focusing on the costs of avoidance behaviours.