Feeding acidified milk to preweaned dairy calves is a popular method to reduce bacterial contamination in milk and promote ad libitum feeding, especially in group housing systems. The objective of this study was to evaluate calf drinking behavior when offered acidified milk versus non-acidified milk. Ten one-day-old Holstein heifer calves were offered either acidified or non-acidified milk on alternating days, with milk on day 1 randomly assigned. The study concluded upon weaning (6 wk of age). Calves were offered 4 L of milk (per feeding) daily at 5:30 and 14:00. The amount of milk refusals were recorded at every feeding for each calf. Calf behavior was recorded during each feeding using video cameras and body weights were recorded every 7 d until weaning. Video footage was analyzed to document the amount of time required to finish drinking and the number of breakaways (calf stopped drinking, remained in the feeding area, and then proceeded to drink) for each calf. Data were analyzed as a randomized complete block design with repeated measures using SAS. The type of milk offered during Day 1 did not affect overall ADG (P = 0.77). When offered acidified milk, calves refused 2.50 ± 0.12 L more milk (P < 0.0001) and demonstrated 0.45 ± 0.11 more breakaways (P < 0.0001) during feedings than when offered non-acidified milk. As calves aged, they refused less milk (P < 0.0001) and demonstrated fewer breakaways during feedings (P < 0.0001). Holstein calves in this study exhibited more aversive behaviors toward acidified milk than non-acidified, unpasteurized milk; however, the frequency of these behaviors decreased as calves aged. When feeding ad libitum acidified milk to group-housed calves, it is important to monitor individual calf behavior to ensure all calves are drinking sufficient amounts to promote good health and growth.