The effects of predation risk on the reproductive behaviour of male and female sand gobies, Pomatoschistus minutus, were investigated in two separate aquarium studies. In the presence of a predator (cod, Gadus morhua), males decreased their courtship activity while females did not alter their level of activity. In the second study, there was no difference between treatments (with and without predator) in the time from when a female was presented to a male with a nest until spawning took place or in the amount of eggs laid. However, pre-spawning behaviour differed between the two treatments. When the cod was in sight, both males and females burrowed in the sand more often. In the absence of a predator, pairs spent longer together in the nest before spawning started, and females also inspected the nest alone, which never happened during predator presence. Hence, both sexes make trade-offs between predator avoidance and behaviours associated with mating. Females, however, seem to take higher risks during the courtship phase in order to find a partner compared to males.