The current study explored the response of llamas to familiar and unfamiliar humans under housing and management conditions typical of both zoological gardens and llama farms. A group of five adult llamas was exposed to three 30-min socialization sessions with one female handler, who offered food and tactile contact. Subjects were then tested for their responses to the familiar handler (A)versus a stranger (B) in an Aj-B-Aj design. Proximity to the handler, sampled at 5-sec intervals through the 1-min test exposures, was used as a dependent variable. For both the A,-B and B-A^ comparisons, the number of animals present in the test area was significantly lower in the presence of the unfamiliar human (p < 0.001; 2-tailed Randomization Test). This finding has important implications for llama housing and management, where individual humans may serve as discrete conditioned or discriminative stimuli if repeatedly paired with hedonic events. Such human-based itioningmay affect animal behavior, physiology, and motivation. Interactions with humans may thus potentially confound experimental results in a research environment, or be used to facilitate eanagement or training.