The 1978 edition of Copa Libertadores was won by Boca Juniors, of Argentina for the second straight year, after defeating Deportivo Cali of Colombia in the final. The defending champions won the two-leg final 0–4 on aggregate, with all four goals coming in the second-leg match after the first leg ended in a goalless draw.

Qualified teams

Draw

The champions and runners-up of each football association were drawn into the same group along with another football association's participating teams. Three clubs from Argentina competed as Boca Juniors was champion of the 1977 Copa Libertadores. They entered the tournament in the Semifinals.

Group stage

Group 1

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Tiebreaker

Group 2

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Group 3

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Group 4

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Group 5

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Semi-finals

Group A

Group B

Finals

Champion