This is data from a survey of United Kingdom Clinical Research Collaboration (UKCRC) registered Clinical Trial Units (CTUs) carried out in November 2018. It asked questions about central and on-site monitoring in phase III randomised CTIMPS.A paper detailing the methodology and findings has been published: Love, S.B., Yorke-Edwards, V., Lensen, S. et al. Monitoring in practice – How are UK academic clinical trials monitored? A survey. Trials 21, 59 (2020)Screenshots of the online survey, a variable dictionary, and the cleaned, anonymised dataset are provided. Both the data and the variable dictionary are provided in .txt files, with columns separated by | [pipe/ vertical bar]. The screenshots are provided as a .pdf fileIn Version 2 the filename for the Questionnaire was updated: the contents remain unchanged. In Version 3 the description and references were updated to include the publication associated with this dataset.