This paper presents a summary of the evidence review group (ERG) report into the clinical effectiveness and cost-effectiveness of infliximab for moderately to severely active ulcerative colitis (UC) based upon a review of the manufacturer's submission to the National Institute for Health and Clinical Excellent (NICE) as part of the single technology appraisal (STA) process. The submission indicated that the efficacy of infliximab (5 mg/kg) had been demonstrated in terms of higher response rates and a sustained response in health-related quality of life. For the cost-effectiveness analysis, the manufacturer built a Markov model to compare infliximab with standard care. It estimated the incremental cost per quality-adjusted life-year (QALY) gained was between 25,044 pounds and 33,866 pounds depending on the strategy used. The ERG report generally agreed with the evidence on effectiveness of infliximab for subacute exacerbations of UC. However, there were several areas of uncertainty, of which the interpretation of the importance of the quality of life changes in the subacute situation and the assessment of the adequacy of the evidence of effectiveness of infliximab in the acute hospital-based situation were considered pre-eminent by the ERG. This challenged the estimates of cost-effectiveness offered and suggested that there should be a separate assessment of infliximab for acute exacerbations of moderately to severely active UC. The summary of the NICE guidance issued in April 2008 as a result of the STA states that: infliximab is not recommended for the treatment of subacute manifestations of moderately to severely active UC.