The clinical profile, course and complications of familial Mediterranean fever (recurrent hereditary polyserositis) seen in 88 children over a period of 11 years are presented. Forty eight children (55%) started their illness below the age of 5 years, and the mean age of onset was 4.9 years. Peritonitis occurred in 85% of children, arthritis in 50%, pleuritis in 33% and erysipelas-like lesions in 16%. Two children developed renal amyloidosis, and one third of the children were subjected to unnecessary operative surgery, reflecting the diagnostic difficulties. The arthritis was mono-articular in 80% and polyarticular in 20% of children with arthritis, and was seronegative (rheumatoid factor and antinuclear antibodies). Human leucocyte antigen (HLA) typing for the B-27 antigen carried out in ten children with arthritis was negative. The synovial attack showed a wide variation in the clinical presentation, course and duration of arthritis, causing diagnostic difficulties. The difficulties in the differentiation of recurrent hereditary polyserositis (familial Mediterranean fever) arthritis from the common causes of acute and chronic juvenile arthritis and the seronegative spondyloarthropathies are discussed. Of 45 children treated with colchicine, 42 children (93%) achieved a therapeutic response.