The Automatic Registration Toolbox (ART) project is pleased to announce the release of Automatic Temporal Registration Algorithm (ATRA) software for unbiased and symmetric (inverse-consistent) registration of multiple intra-subject T1-weighted structural MRI brain scans. The program is accurate, robust, fast, and easy to operate. Youtube tutorials are provided for installing and running ATRA. The program has been tested for registration of as many as 40 MRI volumes from the same subject (Maclaren et al., Reliability of brain volume measurements: A test-retest dataset) with excellent results. It has also been extensively tested on data from ADNI, MIRIAD and OASIS.