codice:
    Protected Sub REPEATER_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.RepeaterItemEventArgs) Handles REPEATER.ItemDataBound
        If e.Item.ItemIndex Mod 2 = 0 Then
           --ITEM--
        Else
            --ALTERNATING_ITEM--
        End If
    End Sub
Oppure:

codice:
     Protected Sub REPEATER_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.RepeaterItemEventArgs) Handles REPEATER.ItemDataBound
        Dim Riga As RepeaterItem = e.Item
       
        If Riga.ItemType = ListItemType.AlternatingItem Then
            --ALTERNATING_ITEM--
        ElseIf Riga.ItemType = ListItemType.Item Then
            --ITEM--
        End If
    End Sub