Background: Tacrolimus is a common immunosuppressant, approved for the prophylaxis ofrnorgan rejection in renal transplantation .On the other hand INH is a drug used as an antibacterialrnor prophylaxes for those kidney recipients. In Ethiopia, those individuals who underwent kidneyrntransplantation took both INH and Tacrolimus drugs. Nevertheless the effect of INH on thernefficacy of Tacrolimus drugs was not well known in Ethiopia. rnObjective: To evaluate the effect of INH on blood level of tacrolimus drug among kidneyrnrecipient individuals attending St. Paul Hospital, kidney center. rnMethods: An institutional based cross-sectional study was conducted on 14 kidney recipientrnpatients from January to September 2019. The study participants received both tacrolimus drugsrnas an immunosuppressant and INH as a prophylaxis. Clinical and laboratory data including drugrnfunctional tests were recorded at the time of treatment with INH and completion of this treatmentrnafter a week, biochemical analysis was also done. rnResult: The concentration of Tacrolimus drug level with INH prophylaxis was significantlyrnhigher when compared to the concentration after finishing INH prophylaxis; p=0.002. Besides,rnthe liver function parameters were significantly increased when tacrolimus was taken with INH;rnAST; P=0.001, ALP; P=0.001, ALT; P=0.01. Similar effect of renal function test values on thosernpatients taking tacrolimus with and without INH was seen; as Creatine; p=0.001, Urea; p=0.003rnwas significantly higher when compared to the values after INH prophylaxis was finished. Therernwere no statistically significance difference observed in Total bilirubin; p=0.933 and Directrnbilirubin; p=0.710 during and post treatment values. rnConclusion: Kidney recipient patients who used INH prophylaxis showed alteration of LFT,rnRFT and blood concentration of tacrolimus (BCT). Biochemical tests except bilirubin werernsignificantly affected by INH drug.