Just rename the BlockOldref name to BlockNew name. [QUOTE="T.Willey"] Joe, I was trying to work on something that would replace one block[/QUOTE] definition with another, but I couldn't get it to work. I was trying to use the 'CopyObject method, but it only seems to work with an acad document or an acad database, which a block table definition doesn't seem to be either one.[QUOTE] How were you able to do this? or if anyone else knows, could you please advise? Thanks. Tim ps. Here is what I had so far, but it doesn't work. The only thing it[/QUOTE] does is delete the objects form the old block.