Local and co-management approaches are increasingly adopted in marine conservation to increase compliance with rules, which is essential for effective management. Here, we evaluate an innovative approach to increasing compliance with community laws restricting access to permanently closed marine reserves within a locally managed marine area in southwest Madagascar. Drawing upon strong cultural bonds with ancestors and local taboos, permanent reserves were sanctified through a traditional ceremonies in which ancestral benediction was requested during reserve closures. We evaluated the effectiveness of the ceremonies in increasing respect for the rules through structured interviews with 161 fishers and local leaders from 10 villages located near established permanent reserves. Almost half of the respondents believed that respect for the rules is increased by the ceremonies. If this is reflected in actual behaviour change, it will help reduce rule infringement, enforcement costs and social conflict. At a one-off cost of approximately 500 US$ each, we believe the ceremonies provide value-for-money as a conservation intervention in the context of southwest Madagascar.