This study compared 3 different interventions to control Haemophilus parasuis mortality in nursery pigs. Both a commercial and an autogenous vaccine had no significant effect in this farm system. In contrast, a reduction of more than 50% mortality was observed when piglets were inoculated with a live culture of the farm’s virulent strain at 5 days of age. The rationale for this intervention was to increase the number of colonized piglets when still protected by maternal antibodies. The benefits and risks of this intervention are discussed in the report.