Studies of sheep mating behaviour have, in the past tended to concentrate on the statistical parameters associated with mating behaviour and the oopulatory act (Bermant et al., 1969,a,b,c; Haughey, 1959; Hulet et al., 1962,a,b,c; Inkster,1957; Lambourne,1956; Lindsay and Ellsmore, 1972; Lindsay and Robinson,196l; Pepelko and Clegg,l965) and have all but ignored a close analysis of the motor acts of the ram and the ewe and their relationship to one another. The result is a body of knowledge having immediate application, especially in efficiency studies, but lacking a firm foundation so that studies could still be found as recently as 1967 on sheep mating behaviour, that gave brief descriptions of some motor acts that were, and remained, unnamed (Mattner et al.,1967). Banks (1964) drew attention to this situation and although his study did much to rectify this, it was by no means complete. The acoount of Hafez et al. (1969) can be viewed in much the same light - though providing more descriptive information than many other investigations (Bourke, 1967; Lindsay,1966; Lindsay and Fletcher, 1972) including several of his own (Hafez,1951; Hafez, 1952), certain basic inadequacies were still apparent. The inadequacies of previous descriptive studies became especially evident during the preliminary stages of the present study, when it became obvious that the sexual behaviour of sheep was much more complex than the earlier studies had indicated.