It has been shown that immunosuppressive drugs are capable of impairing B cell function following solid organ transplantation. Immunoglobulin abnormalities in organ transplant recipients have been described in literature, but data on graft recipients are still rare. Investigative the pattern of immunoglobulin variation after human solid organ transplantation. This study includes 18 liver transplant patients and 14 renal transplant patients. Serum Immunoglobulin (IgG, IgA, IgM) were assayed by nephelometry before and at different periods after transplantation (one sample during 1-3 days and 2 samples during 1-4 mounts after transplantation). In liver transplant study: Serum immunoglobulin increase (IgG and IgA) was prominent in some patients before transplantation. A rapid drop in IgG and IgA was observed during the first days after transplantation. Serum immunoglobulin remained stable within normal limits during the following months after liver transplantation. In renal transplant study: Serum immunoglobulin (IgG, IgA, and IgM) remained within normal or near normal limits during the time after transplantation in 13 of 14 cases. Hypogammaglobulinemia (IgG) was present in one of our renal transplant recipients. The time course changes of serum immunoglobulin concentrations after solid organ transplantation may be interesting because: 1) Immunoglobulin levels after transplantation may predict the risk of hypogammaglobulinemia and/or infections by capsulated micro organisms. 2) Serum immunoglobulin increase is a feature of chronic liver diseases, so it may add an insight into the pathogenesis of hypergammaglobulinemia of liver diseases.