The need for immunization in solid organ transplant recipient can arise from three factors: immune deficit owing to underlying disease, rejection of the organ graft, and immunosuppressive therapy given after transplantation. As a general rule, primary immunizations should be given as early as possible before transplantation because the immune response to vaccines is decreased in patients with end-stage organ disease. There are three categories of vaccines: Live vaccines--oral polio, vaccinia, bacillus Calmette-Guerin, live oral typhoïd, and intranasal influenza vaccines--are contraindicated in solid organ transplant recipients. The use of varicella vaccine remains controversial. The use of rubella vaccine is recommended in young women of childbearing age. Of the killed vaccines or genetically engineered vaccines, the following are recommended: pneumococcal vaccine, influenza vaccine, hepatitis A vaccine, hepatitis B vaccine, diphtheria, and tetanus vaccine. Vaccination of household contacts and health care workers in transplant centers is recommended. However, live vaccine (with the exception of varicella vaccine) should be avoided in these contacts.