The increasing problem of antibiotic resistance has been related, among other factors, to the extensive use of antibiotics in pig farming. To be able to reduce antibiotic usage in this type of livestock breeding, it may be important to know which internal characteristics of farmers are related to their antibiotic treatment practices, next to the external characteristics, such as husbandry conditions. We conducted a survey among Swiss farmers of fattening pigs to investigate their attitudes and habits related to antibiotic usage, as well as their perception of antibiotic resistance and of policy measures intended to reduce antibiotic usage in pig farming. In addition, we related farmers׳ personal variables, attitudes and habits, and their farm characteristics to their actual antibiotic usage at three time points during the fattening period. The farmers in our study appeared to be little aware of the risks of antibiotic usage in pig husbandry. Results seemed to imply that different attitudes and habits were related to antibiotic usage at the three time points during fattening. At the beginning of the fattening period, the farmers׳ habits were mainly related to their antibiotic usage. Perceived risks and cautious behaviour regarding antibiotics were important predictors of farmers׳ perceived impact of policy measures to reduce antibiotic usage. We suggest that promoting habits that reduce antibiotic use among farmers and increasing their risk awareness related to antibiotics in pig husbandry will most likely reduce the use of these substances in pig farming.