After 2 weeks of ingestion of 130 g L-Tryptophan a 52 year old female developes an Eosinophilia Myalgia Syndrome with acute onset of deep venous thrombosis of forearm and possible initial cardiac manifestation featuring intermittent sinustachykardia. This is followed by a severe chronic disease (follow-up 15 months) with diffuse scleroderma and sensomotoric polyneuropathia. The deep muscle biopsy-specimen shows mononuclear infiltration of fascia and interstitial myositis with rare eosinophils. A blood eosinophilia (900/ul) occurs only in the initial acute onset of the illness. Plasma level of Kynurenine is significantly high (4000 pmol/ml), collagenneosynthesis is activated (Pro-collagen type III peptid 0,927 U/ml). No significant clinical improvement was seen with Acathioprine (100 mg/d) and Prednisolon (40-60 mg/d), after treatment with Ciclosporin scleroderma regresses completely, polyneuropathy is persisting.