Return value only if all words are uppercase

This should do it:

Sub Test()
Dim l As Integer
Dim Text As String

lastrow = ActiveSheet.UsedRange.Rows.Count

For i = 1 To lastrow
    Text = Cells(i, 1).Value
    l = Len(Text)
    For x = 1 To l
    If Mid(Text, x, 1) Like "[A-Z]" Or Mid(Text, x, 1) Like " " Then
        Cells(i, 2).Value = "TRUE"
    Else
        Cells(i, 2).Value = "FALSE"
        Exit For
    End If
    Next x
Next i
End Sub

It assumes all your input values are in row 'A', and will then output True/False in Row 'B'.

Let me know if it works!