Code:
Connected to:
Oracle8i Enterprise Edition Release 8.1.7.1.1 - Production
With the Partitioning option
JServer Release 8.1.7.1.1 - Production

SQL> select
  2    d.dname,
  3    (select max(e.sal) from scott.emp e
  4       where deptno = d.deptno
  5    ) as max_dept_sal
  6  from scott.dept d;

DNAME          MAX_DEPT_SAL
-------------- ------------
ACCOUNTING             5000
RESEARCH               3000
SALES                  2850
OPERATIONS

SQL>
Perhaps you should post your exact query....