Four issues concerning the mechanisms of cancer pain are highlighted in this article. First is the need for a common language-a staging system-for assessing cancer pain. The author discusses the recently proposed Edmonton Staging System for Cancer Pain which classifies patients according to seven prognostic factors. The other issues addressed include: Optimal use of narcotic analgesics and adjuvant drugs; and intractable pain syndromes. All are areas of pain management where we are falling short.