The 1978 Pacific Southwest Open, also known under its sponsorship name 1978 ARCO Open, was a men's tennis tournament played on indoor carpet courts at the Pauley Pavilion in Los Angeles, California in the United States. The event was part of the Grand Prix tennis circuit. It was the 52nd edition of the tournament and was held from September 18 through September 25, 1978. Seventh-seeded Arthur Ashe won the singles title as well as 200 ranking points.[1]
Arthur Ashe defeated Brian Gottfried 6–2, 6–4
John Alexander / Phil Dent defeated Fred McNair / 
Raúl Ramírez 7–6, 6–3