The San Marcos Stakes is an American Grade II Thoroughbred horse race held annually, typically in late January at Santa Anita Park in Arcadia, California. Open to horses aged four and older, it is raced on turf over a distance of one and one-quarter miles.

Inaugurated in 1952 as a one mile race on dirt, in 1954 it was changed to one and one-quarter miles and became Santa Anita Park's first graded stakes race on turf. It was raced on dirt again in 1956, 1962, 1969, 1973, 1975, 1978 through 1983, and in 1996. Run as handicap prior to 2000, it was open to three-year-olds and up from 1955 through 1959. There was no race held in 1970 and for 1978 it was set at a distance of 1 and one-eighth miles.