Ultimate Spinach III is the third and final studio album by the American psychedelic rock band Ultimate Spinach, and was released on MGM Records in 1969.

A few days before the production for Ultimate Spinach III began in late 1968, the group was disbanded for personal differences with their record producer Alan Lorber. However, the third album needed to be produced due to contractual obligations with MGM Records.

Lead vocalist/guitarist Barbara Hudson and drummer Russell Levine remained with Ultimate Spinach despite the official disbanding. The Ultimate Spinach sextet was completed with four new musicians from other Boston local rock bands.

This album had no input from Ian Bruce-Douglas. Ted Myers and Tony Scheuren, ex-bandmates in Chamaeleon Church, wrote most of the songs (either individually or collaboratively), while the rest of the band was reunited only for exhausting rehearsals and recording sessions, made in just nine days in Mayfair Studios, New York, in December 1968. The result was a mix of psychedelic, hard rock and pop styles.

After the critical and commercial failure with this record, Ultimate Spinach was disbanded in mid-1969.