In a large European trial, a deworming program using 30 ppm flubendazole for 5 days every 5 weeks forfattening pigs was evaluated for a period of 16 months (4 rounds) and compared with untreated control andhistorical pre-treatment data from the same fattening units. The treatment regime was evaluated in 4 fatteningfarms located in Belgium, The Netherlands and France with a total of 21,721 fattening pigs in the treatedand 22,394 in the control groups. All the farms, except farm A, had very low EPGs (Eggs Per Gram) forAscaris suum before treatment and were nihil after treatment. In three of the farms a reduction in affected andrejected livers due to “white spots” was noted. In all the farms, positive effects on average daily weight gain(15.1 to 34.7 g) were obtained, except in farm C, and fewer dropouts were counted in the treated groups.