I used to use Frontline Plus. I now use K9 Advantix. Both work very well for me. I never find fleas on my dog, and although ticks seem to find him everytime we go afield I have never had one attach itself to him since I started using these products. I switched from Frontline Plus to K9 Advantix because Advantix is formulated to repel mosquitoes as well as fleas and ticks. It seems to do this quite well so far. I noticed, last summer, that after switching to the Advnatix the little nats that used to pest my dog unmercifully do not bother him anymore.