Large population-based studies have shown a significant association between melanoma and lymphoid neoplasia, particularly non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukaemia (CLL), that is independent of any treatment received for the Initial tumour. This study examines the presentation, diagnosis, treatment and progress of three patients who developed advanced melanoma concurrently with a lymphoid neoplasm (one NHL, two CLLs), in order to illustrate their association, discuss common aetiological factors and examine possible therapeutic options. As it is the melanoma rather than the lymphoid neoplasm that represents the bigger threat to overall survival, Initial treatment should be targeted towards this cancer, However, because of the interplay between the diseases and the possible side-effects of the various treatments, the choice of adjuvant therapy requires careful consideration. Immunosuppression associated with chemotherapy may permit a more aggressive course for the melanoma, while locoregional radiotherapy is contraindicated following lymph node dissections. As immunotherapy is of benefit in the treatment of melanoma and has also been recently shown to be effective in the management of lymphoid neoplasia, we instituted interferon-a as adjuvant therapy for these patients, thereby utilizing a single agent to treat the dual pathologies. The three patients have now been followed-up for 6 months without evidence of disease recurrence or progression. (C) 2001 Lippincott Williams & Wilkins.