>>The UNION select can have only one ORDER BY and it's applied to the result set. Try

SELECT * FROM ;
>>	( select TOP 50 * FROM MYTABLE ;
>>		WHERE (&cFilter.) and MY_PK < nPk ;
>>		order by PK ;
>>	) dt1 ;	
>>UNION ALL ;
>>SELECT * FROM ;
>>	(select TOP 50 * FROM MYTABLE ;
>>		WHERE (&cFilter.) and MY_PK > nPk ;
>>		order by PK DESC ;
>>	) dt2
>>

>
>Sergey,
>
>Thank you very much for explanation and for the code.

Also you put DESC in the wrong query's ORDER BY.