Introduction: Intra-seasonal start of treatment with the SQ Ò grass sublingual immunotherapy (SLIT) tablet (GRAZAX Ò , ALK, Denmark) has been previously demonstrated to be well-tolerated. The objective of our study was to investigate the tolerability of intra-seasonal start of treatment comparing patients treated by allergists and general practitioners experienced in treatment of allergy (GPs). Methods: In a non-interventional, open-label, observational study, data on intra-seasonal start