TwO cases of megaloblastic anaemia, of which one was very severe, occurring in women who had been taking oestrogen-progestogen oral contraception over a long period of time, are reported. The authors take the opportunity, after having reviewed the literature, of pointing out the role of oestro-progestogen products in bringing about vitamin deficiencies. They discuss how and where oestrogen-progestogen products work on folic metabolism and emphasize that there is an associated factor which starts off the deficiencies.