The 1978 Belgian Grand Prix was a Formula One motor race held on 21 May 1978 at Zolder.

The 70-lap race was won from pole position by Mario Andretti, driving the new Lotus 79.

The main news before the Belgian Grand Prix was that the new Lotus 79 was now ready to race, and immediately Mario Andretti showed its pace by taking pole comfortably from Carlos Reutemann and Niki Lauda.

He converted it to a first-corner lead, whereas Reutemann had a bad start and got swamped by the field, causing a chain reaction in which Lauda was hit by Jody Scheckter and had to retire.

Andretti cruised to an untroubled victory, with Peterson making it a Lotus 1–2, and Reutemann completing the podium.