Because of its fast scan speed, multi-detector row CT (MDCT) imposes a challenge to optimization of contrast enhancement and scan timing. However, when this challenge is overcome with the use of precisely designed protocols, MDCT provides us with an opportunity to use contrast medium more efficiently and flexibly than with single-detector row CT (SDCT). To fully achieve the benefits of MDCT, it is crucial for radiologists and technologists to 1) understand the factors that determine contrast enhancement and scan timing for MDCT, and 2) identify the required modifications in protocol design to optimize contrast enhancement for MDCT. Clinical considerations for CTA and hepatic imaging are described in this article.