The following non-IEOR courses are highly recommended for students seriously interested in PhD in operations research. These can be taken towards PhD minors in EECS, Math, Statistics, Economics, Civil & Env Engineering.

EECS Courses

CS170 Efficient Algorithms and Intractable Problems
CS172 Computability and Complexity
CS174 Combinatorics and Discrete Probability
CS270 Combinatorial Algorithms and Data Structures
CS271 Randomness and Computation
CS276 Number Theory and Cryptography
CS277 Concrete Complexity
CS278 Machine-Based Complexity Theory
CS282 Algebraic Algorithms
EE227A Introduction to Convex Optimization
EE227B Convex Optimization and Approximation

Math Courses

MATH 104 Introduction to Analysis
MATH 105 Second Course in Analysis
MATH 110 Linear Algebra
MATH 113 Introduction to Abstract Algebra
MATH 170 Introduction to Optimization
MATH 172 Combinatorics
MATH 220 Methods of Applied Mathematics
MATH 221 Advanced Matrix Computations
MATH 249 Algebraic Combinatorics
MATH 250A Groups, Rings, and Fields
MATH 250B Multilinear Algebra and Further Topics

Statistics Courses

STAT200A-200B Introduction to Probability and Statistics at an Advanced Level
STAT205A-205B Probability Theory
STAT206A-206B Stochastic Processes
STAT232 Experimental Design
STAT238 Bayesian Statistics
STAT230A Linear Models

Econ Courses

ECON201A-201B Economic Theory
ECON202A-202B Macroeconomic Theory
ECON207A-207B Mathematical Economics
ECON206 Mechanism Design and Agency Theory

Civil & Environmental Engineering Courses

CEE251 Operation of Transportation Facilities
CEE258 Logistics

See href=http://www.berkeley.edu/catalog/ for more.