Background and aim: The background and purpose of this research is to clarify the differences and similarities between the Iranian legal system and FIDIC regarding the management of force majeure and hardship and to analyze how these concepts affect the rights of the parties to the contract.

Methods: This research is of a theoretical type and has been carried out using a descriptive-analytical method.

Ethical considerations: In this research, the principles of trustworthiness, honesty, neutrality and originality of the work have been respected.

Results: Force majeure and hardship in Iranian and FIDIC law have similarities in general aspects, but there are significant differences in the details and implementation of these concepts, which can emphasize the need to formulate up-to-date and flexible contractual clauses to properly protect the rights of the parties in changing circumstances.

Conclusion: In Iranian law, force majeure generally refers to natural and unforeseeable events whereby the parties can be exempted from their contractual obligations, while hardship refers to economic or social changes that are usually foreseeable but can have severe effects on obligations. In the FIDIC legal system, there are specific clauses to address force majeure that allow the contractor to extend the contract period and be exempted from performing obligations in the face of uncontrollable circumstances, while the effect of hardship requires strong documentation and reasons to justify changes in the terms of the contract.