Background: The Grazax Asthma Prevention (GAP) trial has recently demonstrated significant reductions in the odds of asthma symptoms or medication use in patients treated with SQ^® grass SLIT-tablet relative to placebo, both in combination with allergy and asthma pharmacotherapy. The objective of the present analysis was to evaluate the cost-effectiveness of SQ grass SLIT-tablet relative to placebo in children with AR from the perspective of a German healthcare payer. Methods: A cost-utility model was developed in Microsoft Excel (Microsoft Corporation, Redmond, WA, USA) to evaluate the cost-utility of SQ grass SLIT-tablet in combination with pharmacotherapy versus pharmacotherapy alone in patients with AR. Transition probabilities were derived from the GAP trial, and costs were taken from a real-world insurance database analysis. Future costs and effects were discounted at 3% per annum, and extensive deterministic and probabilistic sensitivity analyses were performed. Results: Over a 10-year time horizon, the base case analysis showed an increase in overall treatment costs of €897 per child being treated with SQ grass SLIT-tablet relative to pharmacotherapy alone. The increased treatment costs were accompanied by an improvement in patient quality of life of 0.10 quality-adjusted life years (QALYs) yielding an ICER of €8978 per QALY gained, falling well below a willingness-to-pay threshold of €17,800 per QALY gained. The base case results were insensitive to changes in all individual model parameters. Discussion: Improvements in quality of life with the SQ grass SLIT-tablet would be accompanied by only a modest increase in costs over a 10-year time horizon, with the SQ grass SLIT-tablet therefore representing excellent value for money from the German healthcare payer perspective.