Abstract: Strptococcus equi which is a Gram-positive bacteria causes strangles a highly contagious disease that affects the respiratory system of the horse. The disease is characterized by fever, nasal discharges and enlargement of the lymph nodes in the head and upper neck region. The aim of this study was to determine the prevalence of S. equi infection among horses residing on horse farms in the main regions of the Kingdom of Saudi Arabia. To achieve this aim, field visits were made to horse farms in Al-Ahsa, Dammam, Jubail, Riyadh, Jeddah, Hafr Al-Baten, Al-Baha and Al-Tayf. A total of 103 farms that contained 1343 horses were investigated. Farm owners and managers were questioned regarding the presence of signs similar to strangles. In the meantime, serum was collected from 181 horses. This initial survey indicated no horses had clinical signs of strangles. However, serologic work detected antibody titer against S. equi in 52 horses (>28%) of which 12 horses had highly significant titer. These horses were located in several locations around Saudi Arabia. It is very likely that the disease has been underdignaosed.