The study of Hox genes is crucial not only in exploring the enigma of homeosis but also in understanding normal development at the fundamental molecular level. "Hox Gene Expression" starts with the amazing discovery of the homeobox twenty-three years ago and follows the exciting path thereafter of a series of breakthroughs in Genetics, Development and Evolution. It deals with homeotic genes- their evolution, structure, normal and abnormal function. Researchers and graduate students in Biology and Medicine will benefit from this integrated overview of Hox gene activities.