The 1977 London–Sydney Marathon, officially Singapore Airlines Rally London-Sydney 1977, was the second running of the London-Sydney Marathon. The rally took place between 14 August and 27 September 1977. The event covered 19,000 miles (30,000 km) through Europe, Asia and Australia. It was won by Andrew Cowan, Colin Malkin and Mike Broad, driving a Mercedes-Benz 280E.