Antimalarial agents, particularly hydroxychloroquine, are fre- quently used drugs in rheumatology, particularly in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). A growing awareness of increased malignancies in these auto- immune rheumatic conditions has raised suspicions that drugs may alter cancer risk in such patients. In vitro, antimalarial agents have been invoked as potentially increasing1 or decreas- ing2 neoplastic processes in breast cancer cells. It has also been suggested that these drugs may decrease the in vitro activity of lymphocytic leukaemia cells.3 However, there exists no defini- tive literature to show any explicit effect of antimalarial agents on cancer risk in clinical populations.