Thanks for the reply. This takes about the same 1000 seconds as the original query. I think the speed issue has to do with the use of a cursor vs. a table even though the cursor exists on the hard drive the same as the table does.

>>In VFP 6, two free tables, table1 (739,068 records) and table2 (609,862 records) each has a fieldx which is a 7 byte long character representation of a number which is unique within each table. Each table has an index tag on fieldx. The following:
>>
>>SELECT fieldx FROM table2 WHERE fieldx NOT IN (SELECT fieldx FROM table1)
>
>Try following query:
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>SELECT fieldx FROM table2 WHERE NOT EXISTS (SELECT fieldx FROM table1 where table1.fieldx=table2.fieldx)
>
>If table1 and table2 indexed by fieldx field, you should have good speed.
>
>
>>
>>This correctly return 31,183 records in 1002.50 seconds.
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>>SELECT fieldx FROM table1 INTO CURSOR tab1 NOFI
>>SELECT fieldx FROM table2 INTO CURSOR tab2 NOFI
>>SELECT fieldx FROM tab2 WHERE fieldx NOT IN (SELECT fieldx FROM tab1)
>>
>>This correctly return 31,183 records in 25.60 seconds.
>>
>>Before each run I made sure that VFP was the only process running on the Windows 95 machine. Pretty strange.