The T77 made its World Championship debut at the 1965 Monaco Grand Prix, where McLaren finished fifth and Rindt failed to qualify.

Jochen Rindt remained, driving the new T81, initially teamed with Richie Ginther, and then by John Surtees following his acrimonious departure from Ferrari.

Rindt's car was sold on and fitted with an ATS 2.7 litre V8 engine.

Jo Bonnier practiced it at the 1966 French Grand Prix but found it too slow.

Starting twentieth, he did not finish the race because of an oil pressure problem.