How are you displaying your results?
Combo box
> properties > data tab> bound column = 1 (Assumes first column of query is record id)
>Properties>Format>Column Count = 2 (Assumes there are 2 columns in your query)
>Properties>format>Column Widths = 0,3 (Hides column 1, displays column 2)
Table
Design view>select lookup field
Click lookup
change display control to combo box
Add query sql to row source
bound column = 1
column count = 2
Column widths = 0,2 (as above hides query col 1, and show query col 2)