Sanchai Ratiwatana (born January 23, 1982 in Bangkok) is a professional tennis player from Thailand. He turned professional in 2004.

In 2007 Sanchai and his twin brother Sonchat won their first ATP doubles title in Bangkok, defeating Michaël Llodra and Nicolas Mahut in the final. They won their second title at the Chennai Open in India, 2008.

He reached World No. 53, his best doubles ranking, on January 28, 2008.