| Zero{suppressed binary decision diagrams (ZBDDs) have been introduced by Minato in 14]{{17]. Here the structural properties of ZBDDs are worked out and a generic synthesis algorithm is presented and analyzed. It is proved that ZBDDs can be at most by a factor n+1 smaller or larger than ordered BDDs (OBDDs) for the same function on n variables. Using ZBDDs the best known bounds on the number o...