Inflammatory bowel disease is an idiopathic chronic inflammatory process of the gastrointestinal tract. The aetiology remains unknown but probably involves a combination of genetic susceptibility, environmental triggers and abnormal immune regulation. Immunomodulators are effective in treating inflammatory bowel disease. Azathioprine and 6-mercaptopurine (6MP) are the most frequently used immunomodulator agents. These agents are probably underused by many clinicians because of concerns about myelosuppression, pancreatitis, allergic reactions and hepatotoxicity, which can occur in a fraction of patients taking these drugs. Therefore, clinicians have sought ways to optimize therapeutic response and limit toxic side effects. Neutropenia, although uncommon, can occur in patients taking azathioprine or 6MP. The question of neutropenia effecting clinical response has been raised as a possible indicator of therapeutic response. In the study from Campbell and Ghosh  in this issue of the European Journal of Gastroenterology and Hepatology, no difference in relapse rates was noted between neutropenic and non-neutropenic patients. In fact, severe life-threatening neutropenia was seen in four patients.