A case of a girl followed up for 18 years is reported. At the age of two, the patient presented psoriasis and coeliac disease confirmed by biopsy and by laboratory data. She followed a coeliac diet and at the age of twelve she manifested a rheumatoid arthritis of the left knee without pain, confirmed by laboratory data (RA test, ANA test). In this period, the patient underwent another gastrointestinal biopsy after suspension of the diet; the structural alterations of the gastrointestinal tract being always present, she continued the diet associated with non steroidal antiphlogistic drug therapy for rheumatoid arthritis. The Authors remark the association of diseases, making a comparison with literature data and confirming the current hypotheses. It is interesting to observe that when the patient presented articular symptoms, there was the reappearance of the gastrointestinal symptomatology. Very interesting is the presence of psoriasis: in fact there is the problem whether this case is a psoriatic arthritis with coeliac disease or a juvenile rheumatoid arthritis with coeliac disease and psoriasis. At last, the Authors report the good results obtained by coeliac diet and non steroidal antiphlogistic drugs; a complete remission of articular symptoms and a good puberal and intellectual growth have been observed.