Mikulicz's disease represents persistent enlargement of the lacrimal and salivary glands, and autoimmune pancreatitis is shown with diffuse pancreatic swelling. Both diseases are characterized with elevated IgG4 concentrations in the serum and prominent infiltration by plasmacytes expressing IgG4 in the glands. Clinical analyses were performed in 40 patients with systemic IgG4-related plasmacytic syndrome (SIPS) who consulted the doctors in Sapporo Medical University Hospital. Our patients were mainly middle-aged or elderly females. The average age was 58.9 years. The diagnosis was following ; 33 cases with Mikulicz's disease, 3 cases with Küttner's tumor, and 4 cases with IgG4-related dacryoadenitis. Slight dysfunction of lacrimal and salivary gland was observed in about 60% of them. Antinuclear antibodies were detected in only 15% of the cases with SIPS. Almost all, except one case, did not have anti-SS-A or anti-SS-B antibodies. Interestingly, hypocomplementemia was revealed in 30% of them. The complications of SIPS include autoimmune pancreatitis, tubulointerstitial nephritis, retroperitoneal fibrosis, prostatitis, and so on. SIPS is mainly treated by the administration of steroids. We started to prescribe much quantity of prednisolone to the patients with organ failure. The recurrence was admitted in the 3 patients for the followed 16 years. We present here the problems and prospects in SIPS.