On September 21, 1970, Wilhelm was selected off waivers by the Chicago Cubs, for whom he appeared in three games. He was traded back to the Braves for Hal Breeden on November 30, 1970. As the Cubs had acquired Wilhelm late in the season to bolster their playoff contention, the trade back to the Braves was a source of controversy. Commissioner Bowie Kuhn investigated the transaction, and in December ruled that he did not find evidence of impropriety associated with the transactions that sent Wilhelm to the Cubs and quickly back to the Braves.