Panno won the World Junior Chess Championship in 1953, and also won the championship of Argentina the same year. He became a grandmaster at the age of twenty. He had an Elo rating of around 2580 Elo in his prime, and of 2515 in 1986 and 2429 in 2008. Panno has several successes at the tournaments at Mar del Plata. He won the international tournaments in 1954 and 1969 (shared with Miguel Najdorf), and the open tournaments in 1986, 1988, and 1994. Panno tied for first at Lone Pine 1977. He played various more famous grandmasters, occasionally losing to them brilliantly. Panno was the first top world chess player born in South America. He was still active as of 2008, finishing third in the Bobby Fischer Memorial tournament held in Villa Martelli.