The end of my previous message had an error. The urlData[["GO"]] is actually as follows and still gives the list error. > urlData[["GO"]] [1] "http://sioux.fhcrc.org/MIRROR/archive.godatabase.org/latest" > class(urlData[["GO"]]) [1] "character" > mode(urlData[["GO"]]) [1] "character" Thanks, Denise