The importance of the delimitation of maritime borders in the Persian Gulf lies in exploiting common oil and gas fields. There are many oil and gas fields in the Persian Gulf, some of which have been discovered and exploited, but others have not been discovered due to existing differences among regional countries over the delineation of the maritime borders. For example, maritime borders between Iran, on the one hand and Iraq, Kuwait and the UAE, on the other hand, have not yet been delineated. The main point here is that Iran gave significant concessions to Qatar and Saudi Arabia at the time of the delimitation of maritime borders, an issue which has remained unnoticed. Here, some questions are raised. First, what are geopolitical problems which prevented the delimitation of maritime borders in the Persian Gulf? Second, which model could be presented for the delimitation of these borders? Third, what are the concessions made by Iran to Arab countries? The main hypothesis of this article is that the geopolitical problems due to the existence of islands and some territorial claims made by some countries against others are the main factors responsible for the failure of attempts made so far to delineate the maritime borders. Its secondary hypothesis is that Iran, at the time of the delimitation of its maritime borders with some regional countries, has given up a large part of common oil and gas fields, which must have been belonged to Iran, to its unfriendly neighbors, because of the adoption of some unusual techniques.