The passenger lymphocyte syndrome (PLS) refers to the clinical phenomenon of alloimmune hemolysis resulting from the adoptive transfer of viable lymphocytes from donor to recipient during solid organ or hematopoietic stem cell transplant. The aim of the present work was to evaluate the role of PLS in causing post transplantation hemolysis and anemia and their associations to donor passenger lymphocytes chimerism in ABO/Rh minor mismatch recipients of kidney and liver transplantation (tx). The current study included three groups; group I (as control group) were 10 donors and recipients as 5 cases of kidney and liver tx with identical ABO/Rh, group II were 20 donors and recipients as 10 cases of kidney tx with ABO/Rh minor mismatch and group III were 22 donors and recipients as 11cases of liver tx with ABO/Rh minor mismatch. The study design of the current work was performed on two stages , before tx which include: blood grouping, Rh phenotyping and Ab screening, routine labs (CBC, liver and kidney functions) for donors and recipients with assessment of hemolysis (DAT , LDH, bilirubin) for recipients only then short tandem repeats (STR) for donors and their corresponding recipients. After tx on day 15 post operative for all groups and on day 30 post operative for 3 cases of group III as follow up, the same investigations were done as before tx with Ab screening and identification for recipients who showed +ve DAT after tx. Then STR of recipients with analysis of the data to detect lymphocyte chimersim in recipients. The current study results showed that, PLS was 20% in kidney tx recipients (group II) and 54.5% in liver tx recipients (group III), among them the antibodies detected were 10% in (group II) and 18.1% in (group III).The antibodies specifieities were anti B in 3 cases, anti D in 1 case and anti C in 1 case, furthermore, STR confirmed passenger lymphocytes chimerism in the recipients who developed allo antibodies.PLS cases from group III who were treated by blood transfusion with their own blood group showed 9% death on day 7 after tx from acute renal failure and 18.1% rejection after 90 days . In conclusion: PLS was 20% in kidney tx and 54.5% in liver tx , the use of blood products of recipient group after tx and immunosuppression that spares humoral immunity may lead to PLS in solid organs tx with ABO/Rh minor mismatch. PLS can be treated by transfusion with donor group, plasmapharesis , red cell exchange and anti-CD20 monoclonal antibodies. PLS play an important role in immume hemoylsis after solid organs transplantation (SOT); although hemolysis is mild and self-limited, there is also risk of substantial morbidity.