Abstract: The prevalence of strongylosis was found to 31.7 percent being 34.0, 30.0 and 31.0 percent, in stud, tonga and riding horses, respectively. Blood picture of the naturally infected animals showed normocytic and normochromic anaemia. Invermectin at the dose level of 0.4 mg kg–1 completely eliminated the egg burden from day 14 post treatment onward. Similar trend is followed at 0.2 mg kg–1 dose level with a small variation.