When an abort of a transaction occurs, a determination is made as to whether diagnostic information is to be stored in one or more transaction diagnostic blocks (TDBs). There are different types of transaction diagnostic blocks to accept diagnostic information depending on the type of abort and other considerations. As examples, there are a program-specified TDB in which information is stored if a valid TDB address is provided in a transaction begin instruction; a program interruption TDB, which is stored into when the program is aborted due to an interruption; and a program interception TDB, which is stored into when an abort results in an interception.