RECENT observations indicate that a typical globular cluster may contain hundreds of millisecond pulsars1,2. Because millisecond pulsars have some similarities to the Vela pulsar, which is known to be a source of γ-rays, they could also be gamma emitters of modest power. Here I estimate the γ-ray luminosity of globular clusters, assuming that they indeed harbour large numbers of millisecond pulsars. An upper limit obtained by the Cos-B satellite on the γ-ray emission from 47 Tucanae, which contains at least 10 millisecond pulsars1, is too large to constrain the model presented here, but the estimated luminosities are high enough to be detectable by the recently launched Gamma Ray Observatory. In the near future, γ-ray observations will thus be able to test this model, and the theory of γ-ray emission by millisecond pulsars.