The Imperial Iranian Navy was the smallest of the country's military arms, with about 30,000 personnel in 1977 (most of which were at sea). It was in the midst of a rapid increase in personnel to some 40,000 by the 1979 in order to expand its ability to defend the regions sea-lanes.

The Imperial Iranian Navy was organized into three fleets, two in the Persian Gulf (Bushehr and Bandar Abbas) and the other in the Caspian Sea. Throughout the 1970s, the role of the navy had expanded as Iran recognized the need to defend the region's vital sea-lanes.

After many years of being based at Khorramshahr, by 1977 the bulk of the navy's fleet had been shifted south to the newly completed naval headquarter base at Bandar Abbas. Other main bases were: Bushehr, Khoramshahr, Khark Island, Hengam Island, and Bandar Shahpur. Bandar Pahlavi was the major training facility and home of the small Caspian fleet, which consisted of a few patrol boats and a minesweeper. The naval base at Chah Bahar (on the Gulf of Oman) had been under construction since the late 1970s and in late 1987 still was not completed.

The navy's fleet was entirely of foreign origin. Great Britain had traditionally been their main supplier, but during the 1970s American vessels became more evident.

The navy, which had consisted only of coast guard ships of less than 100 tons water dispacement was also expanded after the World War II. In 1949 a frigate (built in 1944) and a mine sweeper (built in 1941) were aquired, and a steady construction programme was introduced. 4 missile destroyers and 4 torpedo boasts for military operations in the Persian Gulf were ordered from the British Shipyard Vosper Thornyeroft, not much later, the contract for the world's largest fleet of military hovercraft was signed with a British manufacturer.