The 1985 Monte Carlo Open, also known by its sponsored name Jacomo Monte Carlo Open, was a men's tennis tournament played on outdoor clay courts at the Monte Carlo Country Club in Roquebrune-Cap-Martin, France that was part of the 1985 Nabisco Grand Prix. It was the 79th edition of the tournament and was held from 1 April until 7 April 1985. First-seeded Ivan Lendl won the singles title and earned $58,000 first-prize money. On the final Sunday he had to finish his semifinal again defending champion Henrik Sundström before defeating Mats Wilander in a 3+1⁄2-hour final.[3][4]