Heartworm disease was previously considered a serious clinical problem only in dogs. Recently, however, the incidence of feline heartworm disease appears to be increasing. Factors contributing to this include increased awareness by veterinarians, a wide host preference by the vector, and the realization that host specificity of Dirofilaria immitis was less than previously thought. The diagnosis offeline heartworm disease can be challenging. Several diagnostic tools are available, however. The purpose of this report is to present an overview of feline heartworm disease with special emphasis on its diagnosis and treatment.