Pregnancy represents an allograft in so far that half of the antigens are foreign to the mother. Therefore, a bidirectional interaction between the maternal and the foetal immune systems must exist, which could be disturbed by pre-existing autoimmune liver diseases. Since nowadays autoimmune liver diseases are increasingly detected as early stage diseases due to modern diagnostic procedures, e.g. in women of childbearing age, and since the number of post-transplant pregnancies has become an issue due to improved survival, questions concerning regnancy, autoimmune liver disease and treatment options with bile acids and/or immunosuppressants are of an ever-increasing interest. This book, the proceedings of a Falk Workshop held in Freiburg, Germany, on June 2, 2002, is certainly unable to give any definite answers to any of the hundreds of still remaining questions in this fascinating field, but hopefully it will help to stimulate and initiate cooperation among immunologists, bile acid researchers, gynaecologists and internists.