The objective of this study was to describe the clinical signs, diagnosis and control of maedi-visna in a sheep flock comprising 34 ewes and one ram. The flock was investigated because a variety of clinical problems, such as weight loss, poor weight gain, reduced fertility, pneumonia, central nervous disease and death, had occured in the previous 12 months. A diagnosis of visna was made in a sheep referred to the clinic. Subsequently, all adult sheep in the flock were blood sampled for serological testing for maedi-visna. Six ewes were seropositive and were slaughtered together with their lambs. Two of the sero-positive sheep had cli-nical signs of pneumonia with marked dyspnoea, which on post mortem examination revealed broncho-interstitial pneumonia, characteristic of maedi-visna. The results of all of the clinico-pathological findings suggested, strongly, that maedi-visna was the cause of the problem. For control, it was recommended that all adult sheep be tested at six monthly intervals for two years and seropositive animals and their offspring slaughtered. In addition, all sheep one year of age which die should be autopsied.