Operations research models, although common in industry, government, and education, have not been widely used in manufacturing. That is changing, however, as operations research is brought to bear on today's extremely complex problems. Manufacturing managers can no longer depend solely on experience, but need the help of quantitative decision support tools. This article illustrates the importance of operations research in manufacturing. It provides examples of the use of operations research in factories and in manufacturing planning and support. It discusses future trends of operations research in manufacturing.