The function of chitin binding protein (CBP) and two isoforms of cathepsin B (cathB1, cathB2) were tested by using RNA interference in the tick I. ricinus. Two different methods have been used to deliver dsRNA for RNAi in ticks {--} injection and capillary feeding. The synthesized dsRNA was used to find out the impact of RNAi in the tick tissues, which were tested by RT-PCR and Western blot. The expression of CBP was successfully silenced by RNAi in the salivary glands. The silencing of cathB1 and cathB2 in the gut was less effective, but still limited tick`s ability to feed.