Thanks a lot, that is roughly what I want. But a couple of follow ups:

Is this efficient/practical if both arrays get to sizes of 10K elements?

The array generated for difference contains elements from both arrays. I wanted those unique to @one AND those unique to @two. Again I can do this by comparing @difference with @one and @difference with @two. But I am running the same code three times. Is it practical?

A.A.

BTW - as for the syntax thing - a good general rule for SOPW would be "first engage brain then type...."