Marcelo Dias Jucá (born 18 September 1963 in Rio de Janeiro) is a former international freestyle swimmer from Brazil. Jucá participated in the 1980 Summer Olympics, in Moscow, where he swam the 400-metre and 1500-metre freestyle, not reaching the finals. At the 1983 Summer Universiade, in Edmonton, he finished 4th in the 400-metre and 1500-metre freestyle, and 8th in the 100-metre butterfly. At the 1984 Summer Olympics in Los Angeles, Jucá finished 9th in the 4×200-metre freestyle, 12th in the 4×100-metre medley, 15th in the 400-metre freestyle, and 17th in the 1500-metre freestyle.