A case of a 21-year old girl with sporadic post-prandial episodes of urticaria-angioedema syndrome of increasing severity is reported. Prick test with common food allergens revealed sensitivity to tree nuts, peanuts and barley. Consequently, careful avoidance of these foods was recommended. Notwithstanding, another episode occurred after some months. A prick by prick test revealed sensitivity to Foeniculum vulgare (fennel), the only ingested food which had not been previously tested. The rarity of incidence, the consequent diagnostic difficulties, and the need for further research on the allergenic profile of Foeniculum vulgare are emphasized.