Condenser performance and reliability have a significant impact on the electric generation of a power plant. Steam condensers are prone to fouling and the reduction in heat transfer that results almost invariably has an impact on product cost. Fouling on the heat transfer surfaces increase the thermal resistance, thus reducing the heat transfer performance and it is possible to appear failures. The paper presents theoretical considerations about mechanism of fouling in steam condensers, models for fouling evolution in time and the effects of fouling to effectiveness of condenser and power plant efficiency.