The aim of present study was to determine the seroprevalence of Dirofilariaimmitis in dogs and cats from Riyadh, Saudi Arabia. Blood samples were collected by cephalicand jugular venipuncture from 294 dogs and 190 cats from Riyadh. Serum samples weretested against circulating D. immitis antigen using DiroCHEK?, SYNBIOTICS Corporation,San Diego, CA 92127, USA and anti-D. immitis antibodies using Green Spring D. immitis IgGantibody ELISA test kit, Shenzhen Lvshiyuan Biotechnology Co., Ltd. Guangdong, China. D.immitis antigens were detected in 7.82% of the dogs and in 1.58% of the cats, while antibodiesagainst D. immitis were detected in 13.61% of the dogs and 2.11% of the cats. In outdoordogs, antigens of D. immitis were detected in 10.33% while antibodies were detected in16.85%. A significant difference in the seroprevalence of D. immitis antibodies in dogs wasreported in the summer compared to the winter (p<0.05). There was no significant differenceobserved in the seroprevalence between males and females dogs. Older dogs (3-6 years)showed higher prevalence of D. immitis antigen compared to younger dogs, in the contraryD. immitis antibody prevalence was higher in younger dogs (1-3 years) compared to olddogs. In cats, the prevalence of D. immitis antigen and antibody was high in males comparedto the females, however, the difference was not statistically significant. There was no effectfor the season and age in the prevalence of D. immitis in cats.