This case study reports a patient with severe interstitial pneumonitis, mild polyarthritis and polymyositis, accompanied by the presence of anti-Jo-1 antibodies diagnosed as antisynthetase syndrome. The concurrence of anti-Jo-1 with anti-Ro/SSA antibodies leads to a more severe form of interstitial lung disease. This patient was referred to our hospital because of life threatening respiratory failure. He was refractory to glucocorticoids and cyclophosphamide, but was successfully treated with two sequential infusions of rituximab. Clinical condition improved very rapidly. Response to treatment was well correlated with a fall of levels of serum soluble IL2-receptor. A decrease in pulmonary disease activity was visualized on PET-scans before and after two sequential rituximab infusions.