I don´t really know about Frontline, but I use monthly Revolution treatment for my three guys. I use the once a month adult cat formula; evidently the kitten formula can also be used (it is cheaper) but the kitten treatment won´t protect against heart worms. My three guys have had monthly Revolution for the last two years and have NEVER had a problem with either fleas or ear mites. They go out in the yard on a regular basis and also share the house with my cat Tony, who also gets Revolution. I suspect that beginning the treatment would also eradicate a present infestation within two to five days. All of that having been said, some may find this to be an "expensive" long-term solution, as at least here in Costa Rica it costs $7 a day. I am not sure what the cost would be in the United States. That having been said, if one CAN afford it, then I highly recommend Revolution to any ferret owners. Cheers, Jay and the gang (Barklay, Timmy, Buster and Tony Cat) [Posted in FML 7109]