“…Despite the possibility of an association between the use of oestrogen and the incidence of thromboembolism (Daniel et al, 1967(Daniel et al, , 1968a(Daniel et al, , 1968bJeffcoate et al, 1968), the evidence is by no means entirely conclusive (Gillibrand and Huntingford, 1968;Gunther and Kohorn, 1968;Llewellyn-Jones, 1968;Drill, 1972;Drill and Calhoun, 1972). A much larger series of cases must be studied before any conclusions can be drawn on whether there is an increased incidence of thromboembolism in subjects treated with oestrogens.…”