You might want to check out my reply here: http://www.sqlservercentral.com/forums/shwmessage.aspx?forumid=8&messageid=202581 CHAR(160) is a non-breakable space and as such considered a "noise" character in SQL Server. At least CAST treats it this way. ISNUMERIC however treats this character as thousands separator.

ISNUMERIC is probably one of the most useless functions in SQL Server, IMHO. ....at least, when you don't need to rely on this weired behaviour.

Jeff, can you give an example where 'a-f' are considered by ISNUMERIC to be convertable to a number?