The Precision in Neuroimaging (PIN) Dataset is a collection of freely available structural MRI data. In Phase I, 20 healthy adults (11 females; aged 20-30 years) were scanned on two occasions three weeks apart on the same scanner using the ADNI-3 protocol. On each occasion, individuals were scanned twice (repetition), after re-entering the scanner (reposition) and after tilting their head forward. At one year follow-up, nine returning individuals and 11 new volunteers were recruited for Phase II (11 females; aged 22-31 years). Scans were acquired on two different scanners using the ADNI-2 and ADNI-3 protocols. The purpose of the dataset is to examine the effect of MRI parameters and physiological variables (such as blood pressure, sleep and time of day) with an ultimate aim of improving MRI processing software. Please see NeuroImage (2021), Hedges et al https://doi.org/10.1016/j.neuroimage.202... Raw MRI data is available from 24 subjects who consented for their data to be publicly available