The clinical response to enalapril in 19 cats with hypertrophic cardiomyopathy (HCM) was evaluated retrospectively. Eleven cats were in congestive heart failure (CHF) at the time enalapril was prescribed, while only one cat was in CHF when the cats were reexamined three-to-six months later. Significant changes in cardiac dimensions were identified echocardiographically. No adverse effects on blood pressure, serum creatinine, or potassium were noted. Although the preliminary data suggests that enalapril is well tolerated and may contribute to some improvements in cats with HCM, controlled, prospective studies are needed to prove the efficacy of enalapril in this disease.