For more than 16 years, mobile computers have been supporting the implementation of clinical trials. A review of 28 articles out of more than 100 clinical trials in which mobile computers have been used elaborates on the advantages and problems of this technology. A comprehensive overview of the various technologies as used in different settings is given, and then the methodology of using mobile devices in comparison to traditional methods is discussed. The considerations that need to be made and things to be avoided in order to conduct a successful clinical trial with mobile tools are listed in detail. This survey leads to the conclusion that mobile devices are very useful in most cases, especially when design and software validation aspects have been taken into account. Furthermore information is given about software validation aspects that are unique to the field of clinical trials.