Sublingual immunotherapy (SLIT) is often discontinued, and many patients do not renew the prescription. We evaluated the reasons for discontinuation and set up an educational/follow-up plan to improve the adherence. In a first phase, the adherence at 4 months was directly assessed. Based on those results, an action plan (education, frequent contacts, and strictly scheduled visits) was developed and tested in other patients. A group of matched patients did not undergo the follow-up plan (controls). In the first phase, involving 252 subjects, at 4 months, there were 30% dropouts, mainly due to side-effects. In the second phase, 149 patients underwent education/follow-up and 90 received no intervention. In the first group, discontinuations at 4 months were 5%, vs 18% in the controls (P = 0.01). After one year, 12% of patients were lost in the first group and 35% in the control group (P < 0.001). An adequate education and a strict follow-up can significantly reduce SLIT's discontinuations.