The ARRIVE guidelines are widely endorsed but compliance is limited. The IICARus Collaboration group sought to determine whether journal-requested completion of an ARRIVE checklist improves full compliance with the guidelines. In a randomised controlled trial, manuscripts reporting in vivo animal research submitted to PLOS ONE (March-June 2015) were allocated to either requested completion of an ARRIVE checklist or current standard practice. The authors measured the change in proportion of manuscripts meeting all ARRIVE guideline checklist items between groups. The findings show that simply requesting that researchers improve reporting is not effective as the request to complete an ARRIVE checklist had no effect on full compliance with the ARRIVE guidelines. Thus, editorial checks of compliance and further measures to mandate checklist completion may be required to see improvements in quality.