The objective of this study was to obtain post-marketing information about the use of infliximab in an ambulatory setting. We studied--retrospectively and prospectively--the case records of patients with rheumatoid arthritis (n=37), psoriatic arthritis (n=5), mixed connective tissue disease (n=1), and ankylosing spondylitis (n=2) who received infliximab (3 mg/kg) from August 2000 to January 2003. Descriptive values were given as percentage, mean or median, and standard deviation or interquartile range. Wilcoxon test was used for paired analysis of pre/post doses of corticosteroids, non-steroidal anti-inflammatory drugs, and methotrexate therapy. A p value < or = 0.05 was considered significant. Forty-five patients were included. A total of 207 infusions were administered. In 4 patients the treatment was permanently discontinued due to severe back pain during the infusion (2 cases) and serious anaphylactic reactions (2 cases). Other adverse reactions occurring during infusions were mild and successfully managed with standard treatment. A case of staphylococcal septic arthritis resolved with standard antibiotic treatment. No patient had evidence of active tuberculosis. One patient with rheumatoid arthritis and chronic renal insufficiency, received treatment with infliximab 1.9 mg/kg, every 30 days, with no changes in renal function. Due to improvement of symptoms, 14/39 (35.9%) patients could decrease the doses of corticosteroids, 15/43 (34.8%) decreased the doses of antiinflammatory drugs and 12/34 (35.3%) decreased methotrexate dosage. Although some questions remain to be elucidated, this case series shows the drug safety profile, the possibility to reduce concomitant drug doses, as well as individual approaches for situations where there are not yet guidelines available, so that rheumatologists have to make decisions based on clinical needs.