Referral and reply letters are common means by which doctors exchange information pertinent to patient care. Twenty-eight semi-structured interviews were conducted exploring the views of oncologists, referring surgeons and general practitioners. Twenty-seven categories of information in referral letters and 32 in reply letters after a consultation were defined. The letters to and from six medical oncologists relating to 20 consecutive new patients were copied, and their content analysed. Oncologists, surgeons and general practitioners Australia wide were surveyed using questionnaires developed on data obtained above. Only four of 27 categories of referral information appear regularly (in > 50%) in referral letters. Oncologists want most to receive information regarding the patient's medical status, the involvement of other doctors, and any special considerations. Referring surgeons and family doctors identified delay in receiving the consultant's reply letter as of greatest concern, and insufficient detail as relatively common problems. Reply letters include more information regarding patient history/background than the recipients would like. Referring surgeons and family doctors want information regarding the proposed treatment, expected outcomes, and any psychosocial concerns, yet these items are often omitted. Consultants and referring doctors need to review, and modify their letter writing practices.