Despite the increasing number of ectoparasiticides for pets and their use, flea infestations of cats and dogs are still widespread in Europe. It is therefore important to assess the maintenance of efficacy of the ectoparasiticides for cats and dogs. The present studies aimed to evaluate the efficacy of monthly treatments using a fipronil/(S)-methoprene combination spot-on (Frontline Combo) on dogs and cats from private veterinary clinics located in seven European countries. The survey was conducted for three months during the flea season 2009. A total of 233 dogs and 180 cats were included. Each animal was treated at Days 0 (Day 0), 30 (D30) and 60 (D60) at the vet clinics. For each animal, at least three flea counts were performed at D0, D30 and/or D60 and/or day 90 (Day 90) in order to evaluate the prevalence of flea infestation and the efficacy of control. At the beginning of the study the prevalence of infested animals was 41.63% (97/233) in dogs and 47.22% (85/180) in cats. At D90, the number of dogs remaining infested fell to 8/211 therefore 91.75% became flea-free. The number of infested cats fell from 85 to 9/173 at D90 therefore 89.41% were cured. All animals still infested at Day 90 were living under epidemiological conditions that favour heavy flea burdens. These results are similar or better to previous studies, indicating the continuous high level of efficacy for fipronil 10 years after launch.