The referendum was held on March 30-31, 1979, less than two months after the victory of the Islamic Revolution led by the late Imam Khomeini.
More than 98.2 percent of eligible Iranians voted “yes” to the establishment of the Islamic Republic in the referendum.
Thus, the Islamic Republic was established in line with the popular motto of the revolution that called for “Independence, Freedom and the Islamic Republic” for the country.
The Iranian nation annually celebrates Farvardin 12 on the Persian calendar, which falls on April 1 in normal years and March 31 in leap years, as the anniversary of the establishment of the Islamic Republic of Iran.
IRGC looks forward to 'brightest' year
On Saturday night, Iran's Islamic Revolution Guards Corps (IRGC) released a statement, saying "contrary to the enemy's evil wish, the 40th year of the revolution will be the brightest for the Islamic Republic of Iran."
"The Islamic Republic, with its revolutionary identity, religious foundation, and enormous underpinning of Alavi and Ashura (creed of martyrdom) cut the hands of foreign powers from the country's affairs," the statement said.
It "presented a new concept of power, centered on the Islamic Ummah, and through giving identity to the disadvantaged and the oppressed, it prepared the ground for disrupting the evil plans of the global imperialists to devour the Islamic world and fully dominate humanity," it said.
The IRGC statement said the Islamic Republic has now turned to "the most important challenge and disturbance of the international arrogance led by the evil, criminal and deceitful America."
"The strength and vitality of the revolution and the Islamic system at the age of 40, despite a constant run of conspiracies by the enemies, is among rare phenomena and meaningful and undeniable facts of the contemporary era," it said.
"The glorious record of the Islamic Republic on the eve of the fifth decade" has amazed both lovers and opponents of Iran and the Islamic Revolution, making it "severely exposed to the threat of invasion of the arrogance front and enemies of the Islamic homeland," it said.
It cited efforts to "insinuate a sense of inefficiency of the system in solving economic and welfare problems of the people, creating a gap between the young generation and the state, challenging the regional influence and the strategic depth of the Islamic Republic in Western Asia and trying to weaken and restrict the country's defense capability to the point of fragility and collapse in the face of an external invasion."