Retinae from rabbits and laboratory rodents are often used as 'models' of the human retina, although there are anatomical differences. To test whether monkey eyes provide a better model, a physiological study of Müller glial cells was performed comparing isolated cells and retinal wholemounts from the cynomolgus monkey, Macaca fascicularis and from man. The membrane conductance of Müller cells from both species was dominated by inward and outward K ⁺ currents. Cells displayed glutamate uptake currents and responded to nucleotides by intracellular Ca²⁺ increases. However, there were also species differences, such as a lack of GABA_A receptors and of Ca²⁺-dependent K⁺ currents in monkey cells. Thus, the use of Müller cells from cynomolgus monkeys may be advantageous for investigating a few specific properties; in general, monkey cells are no more similar to human cells than those from standard laboratory animals.