Abstract Extract MacLaren, Johnston and Voss (1964 MacLaren, A. P. C., Johnston, W. G. and Voss, R. C. 1964. Vet. Rec., 76: 1148–1148. [Google Scholar]), in describing cobalt poisoning in cattle, point out that there are only a few recorded cases (Ely et al, 1948 Ely, R, Dunn, K. M. and Huffman, C. F. 1948. J. anim. Sci., 7: 239–239. [Google Scholar]; Keener et al, 1949 Keener, H. A., Percival, G. P., Morrow, K. S. and Ellis, G. H. 1949. J. dairy Sci., 32: 527–527. [Google Scholar]; Davis, 1957 Davis, G. K. 1957. Trace Elements. Proc. Conf. Wooster, Ohio, 193–193. New York: Academic Press. 1958 [Google Scholar]). Josland (1937 Josland, S. W. 1937. N.Z. J. Sci. Tech., 19: 31–31. [Google Scholar]), and Becker and Smith (1951 Becker, D. E. and Smith, S. E. 1951. J. anim. Sci., 10: 266–266. [Google Scholar]), recorded body weight losses and anaemia in sheep as a result of repeated doses of cobalt given over prolonged periods. Otherwise, there is a similar lack of information for sheep. These facts prompted the publication of results of an experiment carried out by the writer a few years ago. In that experiment the effects of single toxic doses of cobalt sulphate, given to adult ewes, were examined.