Background The present report was a follow-up investigation at 2.5- and 7-year intervals of a previous study of 20 children with moderate-to-severe immunoglobulin E (IgE) mediated hen's egg (HE) allergy who received oral immunotherapy (OIT) with raw HE. The study design of the previous study divided the 20 subjects into two groups of 10 each: (1) group 1, the OIT group (OIT-G), and, (2) group 2, an age-matched control group (C-G). In that study, 8 of 10 of the children in the OIT-G were successfully desensitized, one child was partially desensitized, and desensitization failed in one child. The aims of the present study were to evaluate the long-term effectiveness and safety profile of OIT with raw HE, and to assess the course and prognostic value of skin-prick tests (SPT) and serum-specific HE-IgEs in this study population. Methods Of the 20 children who were recalled, 2 dropped out, which left 18 to be evaluated. Information on their HE intake was recorded, and SPTs with HE allergen extracts and with raw and hard-boiled HE were performed. Ovomucoid- and ovalbumin-specific IgE levels were also measured. Results At the first (2.5-year) and second (7-year) follow-ups, 87.5% of the children in the OIT-G who tolerated raw HE were still tolerant, whereas the children in the C-G were significantly less tolerant. Overall, cutaneous sensitivity to HE significantly decreased after the 6-month desensitization period and at both follow-ups with regard to the OIT-G but not with regard to the C-G. A significant reduction in serum ovomucoid- and ovalbumin-specific IgE levels was seen in both the OIT-G and the C-G. Conclusion Clinical raw HE tolerance induced by OTT persists over time. Negativization of SPTs could be considered a more reliable prognostic indicator of clinical tolerance to raw HE than the reduction in specific-HE IgE levels. Raw-HE OIT would seem to be a promising method to treat HE allergy.