Until recently, the impact that the presence of conspecifics may have on stereotypic behavior in naturally solitary species exhibited in zoological institutions has largely been ignored. This study examined the effect of adding a visual barrier between animal holding areas at the Brookfield Zoo on stereotypic head-rolling behaviour in an adult female okapi (Okapia johnstoni). Instantaneous sampling was used to document the proportion of time the female okapi spent head-rolling prior to and after visual barriers were constructed. Behavioural surveys were