ObjectiveMedication non-adherence in rheumatoid arthritis (RA) is associated with disease flares, increased disability and increased costs. This study assessed the effectiveness of electronic monitoring feedback (EMF) on medication adherence in patients with RA starting with or switching to a new biological disease-modifying antirheumatic drug (bDMARD).MethodsIn this randomised controlled trial, bDMARD starters were assigned to the intervention or control group and followed for 1 year. The intervention group received a needle container with a Medication Event Monitoring System (MEMS) cap registering patient’s adherence to injections. Scores were calculated every 3 months with MEMS and motivational interviewing feedback was given. The control group received usual care. Effectiveness of EMF on adherence was measured with the medication possession ratio (MPR).Results104 consecutive intervention patients were included and 102 controls. MPR was 0.95 (SD: 0.10) and 0.90 (0.16) after 12 months (B: 0.036, 95% CI: 0.001 to 0.007, p=0.045). bDMARD-naive patients receiving EMF achieved low disease activity (LDA) sooner compared with the control group, adjusted for baseline DAS (HR: 1.68, 95% CI: 1.00 to 2.81, p=0.050). Side effects and DAS28 were similar.ConclusionEMF increased adherence for patients with RA starting with or switching to a bDMARD. Especially bDMARD-naive patients achieved LDA sooner compared with the control group, which holds promise for the future.