The acaricidal activity of peracetic acid, PAA, against the cattle tick, Boophilus annulatus, and the fowl tick, Argas persicus was tested using filter paper contact bioassay. PAA had a great potential as acaricide and its effectiveness increased with increasing concentration and exposure time. Two minutes after treatment with 0.5%, PAA induced 100% mortality of bothtick species and LC50 values for cattle and fowl ticks, after treatment for 30 min, were 0.06 and 0.05%, respectively. Following treatment with 0.25%, the LT50 values were 0.02 and 3.12 min, respectively. Furthermore, the detrimental effect of PAA against cattle tick extended beyond the adult stage, it significantly prolonged the preoviposition period, shortened the oviposition period, and decreased the mean number of the layed eggs, such parameters were 14.75 and 6.57 days, as well as 457.50, respectively, after treatment with 0.25% of PAA. Therefore, PAA is highly effective when used at lower doses and short exposure time. The high speed of killing ticks is very important for avoidance of the hazard ensued by pathogen transmission in the course of delayed mortality caused by the currently used acaricides. Key words: Boophilus annulatus, Argas persicus, acaricide, peracetic acid.