Subjects with Nickel sensitization proved by patch test may suffer of contact eczema, but also of a Sistemic Nickel Allergy Syndrome (SNAS) consisting of urticaria-like troubles, itch, erythema, cutaneous rush, headache, intestinal symptoms, recurrent vesicular palmar dermatitis. 160 subjects (130 F, 30 M) were classified into three groups and underwent dosage of Nickel in urines (U-Ni) and blood (B-Ni). The two groups with SNAS showed an higher indicators of Nickel absorption, while the only-eczema group did not. 95 subjects with SNAS were enrolled for a Nickel-scanty diet: most of them improved. 24 ones again symptomatic were admitted to an experimental treatment, by a schedule of oral increasing microdose (nanograms) of Nickel sulphate: all of them improved. In conclusion Nickel pathology is changing, allergy seems to be due to different mechanism, dietary intake is important, an immune-tolerance can be induced.