Iran is located in a seismic prone region with several earthquakes occurring annually causing extensive damage to structures and infrastructure. Guilan province is located in the northern part of the country, exhibiting a large population, moderate climate and extensive river system. This region experiences high humidity, several active faults and high seismic hazard potential. This highlights the importance of an active and extensive maintenance and rehabilitation program for the bridges in this region. Structural Health Monitoring (SHM) is an engineering tool used to control changing conditions of infrastructure providing useful information for management, decision making and in certain circumstances code revision. This paper proposes a method for SHM of bridges. In total, 123 concrete bridges were assessed based on this visual inspection; with statistical analysis of results carried out on decks, piles, abutments, restraints and river engineering which effectively addressed the deficiencies in bridges maintenance. Finally some practical solutions are suggested to enhance the performance and lifetime of bridges. Based on the knowledge of the authors, this is the first comprehensive study on a large group of bridges in Iran which can be used as a base for further studies on management and retrofitting of bridges in the region.