The authors report a patient who presented 4 times a systemic urticaria with arthralgias and fever treated by corticosteroids with efficacy. Wild hop (Humulus lupulus) was finally proved to be the causal factor. H.L. belongs to the cannabinaceas family. Hop dermatitis in hop workers population is the main widely described clinical manifestation. Rhinitis, conjunctivitis, asthma are rare as soon as contact urticaria. IgE-anti Hop induced allergies are described in the literature. However, in some cases of reactions to hop the mechanisms are uncertain: toxicity--possible role of lupuline--or immunoallergic processus with immunocomplexes (IC) (with increased IC in serum) and systemic urticaria such as in our observation.