The species of parasite, low dose, and continual employ of the same drug may predispose to the evolution of anthelmintic resistance AR. In Mosul, Iraq, this is the first study investigating AR in gastrointestinal GIT nematodes of calves. Four hundred eighty fecal samples through a cross-sectional survey were examined using the Mini-FLOTAC. A herd of calves consisting of 60 male calves was divided into four groups of 15 calves: group A counted as control, group B was treated with Reemazol ® 25% (Albendazole) 7.5 mg/kg of body weight orally, group C received Dufazan ® (Levamisole and Oxyclozanide) 7.5 mg/kg BW orally, and group D gave Ivermectin 1% by S/C injection 0.2 mg/kg BW. The efficacy asset employs the Fecal Egg Reduction Test (FECRT). AR judgment obtains relying on the instructions of the World Association of advancement for Veterinary Parasitology (WAAVP). GIT nematode prevalence was 50.6%. The effectiveness of mentioned drugs was 84, 87, and 95%, respectively. The lower limit confidence interval 95% level was 89, 86, and 80%, respectively, indicating AR to albendazole and levamisole, while ivermectin was questionable. In conclusion, the high prevalence of GIT nematodes in Mosul indicate that AR is present against the three classes of deworming drugs. Awareness of the associated aspects and sources of resistance is essential to face and minimize the development of resistant worms.