OBJECTIVE: This in situ/ex vivo study assessed the erosive potential of a light cola drink when compared to a regular one. METHODS: During 2 experimental 14-days crossover phases, eight volunteers wore palatal devices with 2 human enamel blocks. The groups under study were: group light, erosive challenge with light cola drink and group regular, erosive challenge with regular cola drink. During 14 days, erosive challenges were performed extraorally 3X/day. In each challenge, the device was immersed in 150ml of light cola (group light) or regular cola (group regular) for 5min. Erosion was analysed by surface profilometry (microm) and surface microhardness change (%SMH). The data were statistically analyzed using paired t test (p<0.05). RESULTS: Group light (0.6+/-0.2microm) showed significantly lesser wear than group regular (3.1+/-1.0microm). There was no significant difference between the groups for the %SMH (group light -63.9+/-13.9 and group regular -78.5+/-12.7). CONCLUSIONS: The data suggest that the light cola drink is less erosive than the regular one.