Dim a As String = "a|b|c" Dim b As String = "b|c|d" Dim c As String = "d|e|f" Dim ls As new List(of String) Dim arys() = {a, b, c} For Each ary As object In arys For Each s As String In ary.split("|") If ls.Contains(s) = False Then ls.add(s) End If Next Next msgbox(String.join("|", ls.ToArray))