Objectives To audit the proportion of clinical trials that had been publically registered and, of the completed trials, the proportion published.

Setting 2 major research institutions supported by the National Institute of Health Research (NIHR).

Primary and secondary outcome measures The proportion of trials reporting results within 12 months, 24 months and ‘ever’. Factors associated with non-publication were analysed using logistic regression.

Inclusion criteria Phases 2–4 clinical trials identified from internal documents and publication lists.

Results In total, 286 trials were identified. We could not find registration for 4 (1.4%) of these, all of which were completed and published. Of the trials with a registered completion date pre-January 2015, just over half (56%) were published, and half of these were published within 12 months (36/147, 25%). For some trials, information on the public registers was found to be out-of-date and/or inaccurate. No clinical trial characteristics were found to be significantly associated with non-publication. We have produced resources to facilitate similar audits elsewhere.

Conclusions It was feasible to conduct an internal audit of registration and publication in 2 major research institutions. Performance was similar to, or better than, comparable cohorts of trials sampled from registries. The major resource input required was manually seeking information: if all registry entries were maintained, then almost the entire process of audit could be automated—and routinely updated—for all research centres and funders.