Volume 50 of this series covers bicyclic diazepine compounds, discussing each system, first in order of ring fusion and then according to increasing size of the fused ring (least degree of saturation first). The discussions of carbocyclic fused rings precede those of heterocyclic fused rings; however, where appropriate, the benzene annelated ring system is given preference over other fused ring systems. In addition, the great volume of material to be covered for the [e]-fused [1,4]- benzodiazepines has been arranged in five chapters for easy reference. The literature to 1985 has been surveyed for this volume.