The present volume contains papers selected for presentation at the 14th Symposium on Mathematical Foundations of Computer Science - MFCS '89 held in Porabka-Kozubnik, Poland, from August 28 to September 1, 1989. Previous MFCs proceedings have also been published in the Lecture Notes in Computer Science. This volume presents investigations and results in theoretical computer science, in particular in the following areas: logics of programs, parallel and distributed computing, deductive databases, automata and formal languages, algorithms and data structures, software specification and validity, complexity and computability theory.