The foundations are laid for a theory of multiphcatlve complexity of algebras and it is shown how "multtphcation problems" such as multtphcatton of matrices, polynomials, quatermons, etc., are instances of this theory The usefulness of the theory is then demonstrated by utilizing algebratc ideas and results to derive complexity bounds In particular hnear upper and lower bounds for the complexity of certain types of algebras are established KEY WORDS AND PHRASES' computational complexity, mulnphcation problem, multlphcative complexity, evaluatton of bihnear forms, bdmear chain, hnear algebras CR CATEGORIES 5 12, 5 14, 5 25