The use of the WHO guidelines "by mouth, by the clock and by the ladder" is now the mainstay of cancer pain management. Because of the guidelines' simplicity they found general acceptance and helped to establish an international pain therapy standard for worldwide use. Nevertheless, there is no scientific validation of WHO step II. In the absence of prospective controlled randomized trials additional longterm results are necessary. We need more data on the use of WHO step II and an update of the published guidelines taking account of modern sustained-release drugs. Up to now, step II of the WHO guidelines for cancer pain is not a clinical reality but at best a didactic instrument.