http://dev.mysql.com/doc/refman/5.0/en/sqlps.html
like that:
PROCEDURE test.test()
BEGIN
PREPARE stmt1 FROM 'SELECT SQRT(POW(?,2) + POW(?,2)) AS hypotenuse';
SET @a = 3;
SET @b = 4;
EXECUTE stmt1 USING @a, @b;
END
and catch this message:

But in mysql console it works properly.