Case reports have described an association between oral food/aeroallergen immunotherapy with the development of eosinophilic oesophagitis (EoE). The underlying mechanism of this is poorly understood, as is the role that both food/aeroallergen sensitisation plays in the pathogenesis of EoE. Specific immunotherapy has a long-standing history of use in the management of moderate/severe seasonal allergic rhinitis (AR), caused by tree/grass pollens. Subcutaneous immunotherapy (SCIT) to grass pollen is less commonly used in children than sublingual immunotherapy (SLIT) or oral immunotherapy for practical reasons. We describe a case of a child with severe grass-pollen related AR and known, but quiescent, EoE, who developed recurrence of oesophageal symptoms on two separate occasions, coincident with the commencement of SLIT to grass pollen. He was subsequently started on SCIT to grass pollen and developed recurrence of symptoms of EoE-a phenomenon that has yet to be reported in the medical literature.