Kittens were given N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) to deplete cortical noradrenaline (NA) in order to test whether this would affect the results of monocular deprivation. Seven kittens that received DSP-4 systemically had cortical NA depleted by 25 to 98%, and six kittens that received DSP-4 in the lateral ventricle had cortical NA depleted by 72 to 92%. In all of these kittens, suturing shut the eyelids of one eye for 1 to 2 weeks produced a visual cortex in which most neurons responded only or most strongly to the eye that remained open. These results are considered together with previous results from our laboratory on monocular deprivation and NA depletion. There is little difference between the ocular dominance histograms of depleted and undepleted animals and little correlation between the extent of the ocular dominance shift and the extent of NA depletion. We conclude that depletion of cortical NA by itself does not prevent the cortical effects of monocular deprivation and that, where such an effect has been found, it may be due to some other factor.