Modular representations of simple Lie algebras J. E. Humphreys Dept. of Mathematics & Statistics, U. Massachusetts, Amherst, MA 01003-4515 Bull. Amer. Math. Soc. 35 (1998), pp. 105-122. Abstract. In spite of many efforts over the past 50 years, the irreducible representations of the Lie algebra of a simple algebraic group over a field of prime characteristic are poorly understood. Recent work on quantum groups at a root of unity has provided new impetus for the subject. This article surveys what has been done and what remains to be done. In preparing this survey I have benefited from extensive correspondence and conversations with Jens Carsten Jantzen, as well as advice from Ivan Mirkovi\'{c} and Dmitriy Rumynin. To the memory of Boris Weisfeiler.