If it's bath time for your dog, you should actually bathe your dog and let him dry before applying Advantix, and then do NOT bathe him for 72 hours - at least - after applying. Advantix needs several days to "coat" your dog's body through his skin glands. If you bathe it within 24 hours of applying because you "need to", it won't be an effective anti-flea tool throughout the entire month, and you're going to have to use something else, too, which defeats the purpose of using it. It's expensive! And you can't just keep putting more on your dog, it may poison it. So I'd wait until after the bath.