In recent years Bayesian networks have attracted much attention in research institutions and industry. This book addresses persons who are interested in exploiting the Bayesian network approach for the construction of decision support systems or expert systems. The theoretical exposition of the book is self-contained and does not require any special mathematical prerequisites. The book includes a PC-diskette with a restricted version of HUGIN. The diskette includes a tool for building Bayesian networks, a library of examples, and a library of proposed solutions to some of the exercises.