From Wikipedia:

The South Vietnamese units participating in the battle took heavy losses in their failed attempt to destroy the VC forces. South Vietnamese casualties included 83 killed in action and at least 100 wounded. The American participants, who included advisors and aircrews, counted three dead and eight wounded. Of the 15 American helicopters sent to support the operation, only one escaped undamaged, and five were downed or destroyed.

For the VC, the Battle of Ấp Bắc marked the first time they stood and fought a large South Vietnamese formation—despite being outnumbered by more than five to one. Against overwhelming odds, the VC had achieved their first de facto victory; they had successfully held off well-equipped ARVN forces supported by artillery and armored units as well as by American airpower. VC casualties were limited to 18 soldiers killed and 39 wounded, even though their positions had been hit by more than 600 rounds of artillery, napalm, and other ordnance released by 13 warplanes and five UH-1 gunships.