To study the usefulness of urinary 1-methylhistamine and serum tryptase concentration as monitoring parameters in clinical settings, we investigated 32 children with atopic dermatitis and suspected food allergy during oral food challenges with eggs and cow's milk. Urinary 1-methylhistamine (MH) excretion increased significantly within 1 h after positive oral food challenges (p < 0.006), but showed considerable variation in negative challenges. MH seems to be a sensitive parameter (92.8%), but its specificity is insufficient (37.7%). In the group of 16 positive oral food challenges serum tryptase concentration increased significantly (p < 0.02) directly after provocation and remained elevated up to 2 h after provocation. No variation was observed in negative challenges or nonatopic controls. Serum tryptase concentration seems to be specific for marked clinical reactions after oral food challenges (100%), but its sensitivity was low (25%) and not superior to evaluation by clinical means. We conclude that, despite positive results for the group of children, MH and serum tryptase concentrations are not useful parameters for monitoring oral food challenges in an individual child due to insufficient sensitivity and specificity.