Imatinib is a tyrosine kinase inhibitor that is used to treat chronic myeloid leukaemia and has been observed to reduce insulin requirements in patients with diabetes. Subsequent studies showed imatinib normalises glucose in the type 1 diabetes NOD mouse. These observations lead us to perform a randomised controlled trial to determine whether imatinib could improve pancreatic beta-cell function in patients with recent-onset type 1 diabetes. Sixty-seven adult participants were randomised in a 2:1 ratio to imatinib 400mg daily or placebo within 100 days of their diagnosis. The treatment period was six months and the primary outcome was C-peptide response to a mixed meal at 12 months. Forty-three imatinib and 21 placebo participants attended the month 12 visit. When compared to the placebo group, active-arm participants had higher C-peptide at 12 months, used significantly less insulin and had similar HbA1c. There were no differences in the rates of serious side effects although the imatinib participants were more likely to experience mild illnesses, particularly assymptomatic leukopaenia and thrombocytopaenia, and GI disturbance. These findings suggest imatinib may be a useful adjunctive therapy for recent-onset type 1 diabetes. Demonstration of ‘prospect of benefit’ will justify similar studies in children.