On May 1, board chairman Gwyn Morgan will step down form the company, SNC said in a news release Thursday.
Morgan will be replaced by Ian Bourne, a longtime executive at the company who was briefly interim CEO last year.
Three other longtime SNC directors, David Goldman, Pierre H. Lessard and Edythe A. Marcoux, will also step down from their roles in May.
Morgan has helmed the company through one of the most difficult periods in its 100-year existence, an era that started in 2011 when suspicious payments to secure contracts in Canada and abroad first came to light.
Last fall the company's former CEO, Pierre Duhaime, was arrested and charged with fraud in connection with the contract to build the McGill University Superhospital. And just last month a top executive with the company admitted to dubious political donations while testifying at the Charbonneau commission.
There are also indications of suspicious payments to secure engineering contracts in Libya during the regime of former dictator Moammar Gadhafi.
Once the three new directors and new chair are added to the three new directors added last year, SNC-Lavalin will have turned over half of its board since the improper payments scandal broke in 2011.
"Throughout this process, the board aimed to reinforce the corporation's commitment to integrity, and to regain trust among shareholders and the broader stakeholder community," Morgan said.
SNC-Lavalin's profit dropped by 18 per cent in 2012, and the share price lost more than 20 per cent of its value last year.
SNC shares were trading hands at $41.91 in Toronto on Thursday, down roughly nine cents on the day.