Rhesus macaques (Macaca mulatta) are a valuable animal model in neurophysiological experiments due to their advanced cognitive abilities. Due to the complexity of the tasks, NHPs participating in such experiments undergo potentially stressful experimental procedures such as fluid control protocols. The current study aimed to investigate the effect of fluid control on the welfare of 21 Rhesus macaques using behavioural observations of the subjects in their home cages via video recordings. Overall, our data showed no difference in displacement behaviours, pacing and ‘inactive not alert’ behaviour when subjects were under the two conditions, suggesting that fluid control protocols had no effect on the welfare of the subjects.