ReplicationDomain is an online database resource for storing, sharing and visualizing DNA replication timing and transcription data, as well as other numerical epigenetic data types. Data is typically obtained from DNA microarrays or DNA sequencing. Our site has a user registration system that allows registered users to upload their own data sets. While non-registered users may freely view and download public data sets, registered users may upload their own data sets and view them privately, share them with other registered users, or make published data sets publicly available. In addition we have implemented additional mechanisms that allow users to restrict sharing of data sets to a user designated group of registered users. Further details on the database usage are in the User Guide Page, while data set details are in the Documentation Page.