To evaluate the effectiveness of several types of complementary medicine in patients with rheumatic diseases, a literature search was performed. Clinical trials, blind or open, comparing the effectiveness of forms of complementary medicine with that of placebo or another control therapy in patients with rheumatoid arthritis, osteoarthritis, soft tissue rheumatism and the fibromyalgia syndrome were selected until half of 1989, using electronic databases. Abstracts and summaries were excluded. The investigation was performed at the department of rheumatology of the Medisch Spectrum Twente hospital at Enschede in cooperation with the department of internal diseases of the Sint Radboud hospital at Nijmegen. For each type of complementary treatment, the results of all the clinical trials were summarized. Furthermore, the placebo-controlled trials were graded according to convincing trials or trials that seemed to be less valid and/or difficult to interpret. Data concerning acupuncture, balneotherapy, dietary measures, enzymic therapy, Seatone, homeopathy, manual therapy and fever few were found. Of these types of complementary medicine in rheumatic diseases, we found no convincing prove that they are more effective than the control or placebo treatment. A considerable number of the studies however can be criticized. It is necessary to perform further studies on the effect of frequently used types of complementary medicine in patients with rheumatic diseases, by or in cooperation with the physicians or paramedics who prescribe or perform these kinds of treatment. This is nearly always possible; directives are given to realize further studies of this kind. If a particular treatment proves to be no more effective than placebo treatment, its use should be discouraged.