A great deal of research carried out in chemistry is devoted to the study of heterocyclic chemistry. It is a vast and expanding area of chemistry because of the obvious applications of compounds derived from heterocyclic rings in pharmacy, medicine, agriculture and other fields. Several updated reviews on specific topics are available nowadays. First, our experience and the critics who pointed out to the need of written form the book for importance of 4,5,6,7-tetrahydrothieno[3,2-c]pyridine (THTPs). The work has been designed as a book for a complete introduction about the THTPs which can be supportive to all the researcher working with this medically important organic moiety. This book covers the all the aspects regarding to THTPs since we believe in the soundness in our approach. The book consists of three chapters and discuss about the synthetic and medical importance of fused heterocyclic ring systems containing THTPs. Besides, new recent synthesis and reactions of THTPs have been included. We hope this book gives the complete introduction about THTPs to the reader.