In the Knowledge Economy age,the pro portion of mental workers has been in creased remarkably and they are playing an important role in the s ocial progress and economic growth o f the country.In order to motivate th e mental workers their real needs and p referential needs must be understoo d.Based on the above goal this paper makes an empirical research by questionnaire on preferential needs and p otential preferential needs of ment al workers who work in government agencies,ent erprises and public service establishments and of managers,technician s and those who take both technical and adm inistrative positions.The paper co ncludes with recommendation on how t o motivate mental workers effectively.