this volume contains the thoroughly refereed and revised papers accepted for presentation at the ijcai 91 workshops on fuzzy logic and fuzzy control, held during the international joint conference on ai at sydney, australia in august 1991. the 14 technical contributions are devoted to several theoretical and applicational aspects of fuzzy logic and fuzzy control; they are presented in sections on theoretical aspects of fuzzy reasoning and fuzzy control, fuzzy neural networks, fuzzy control applications, fuzzy logic planning, and fuzzy circuits. in addition, there is a substantial introduction by the volume editors on the latest developments in the field that brings the papers presented into line.