This document discusses various in vitro and in vivo models used to assess gastrointestinal effects of drugs during preclinical testing. It describes models for assessing gastric emptying, intestinal motility, gastric secretion, nausea/emesis, and gastrointestinal absorption. For gastric emptying and motility, in vitro models use stomach and gut tissues in organ baths, while in vivo models use meal markers in rodents. In vitro cell-based and ex vivo tissue models are used to study gastric secretion and damage. Dogs and ferrets are commonly used to evaluate nausea and emesis. The Caco-2 cell model and in situ rat gut preparations are discussed for assessing gastrointestinal absorption.