Understanding the behavior of endangered species is crucial to improve the management tools to breed animals in captivity and, thus, to increase the success of ex situ conservation programs. In this study, we monitored suckling behavior of 26 cubs born between 2008 and 2012 at "El Acebuche" Iberian Lynx Breeding Centre. The cubs devoted 251 ± 19.7 min (mean ± SE) to lactation on the day of birth, while mothers spent 426 ± 27 min (mean ± SE) nursing their offspring. The time cubs spent suckling decreased exponentially as they grown, until they were fully weaned at 65 ± 2.6 days. The onset of weaning (first intake of solid food) occurred at 54 ± 1.35 days (mean ± SE). Thus, the strict lactation period occupied most of the overall lactation period. Both suckling and maternal behavior were affected by litter size. In twins and triplets, the competition between siblings caused a decrease in the time spent suckling, in spite of the mothers spending more time nursing their young. Finally, no significant differences were found in time spent suckling between littermates or depending on the sex of the cub. Lactation appeared to play a key role in the nutrition of the Iberian lynx and should therefore be conveniently managed in captive breeding programs of this threatened species. Zoo Biol. 35:216-221, 2016. © 2016 Wiley Periodicals, Inc.