For patients with lupus nephritis, a 24-month course of intravenous cyclophosphamide has been advocated as the 'golden' standard of therapy. This regimen is associated with a high risk of persistent amenorrhoea in women or azoospermia in men. The risk of infertility is thus an important issue when discussing treatment options in patients with SLE. In this article I have summarised the information on cyclophosphamide-induced gonadal toxicity. In addition a brief overview is given of the literature on treatment of lupus nephritis. The data indicate that there is no hard evidence to support the superiority of long-term i.v. cyclophosphamide. Therefore, patients with SLE and the wish to have a baby should not be primarily treated with such a regimen.