The present article examines the ideas of two eminent scholars in the Qajar era who were pioneers in presenting some issues and concepts regarding the population. The former, A. Najmoldoleh, was a distinguished mathematician, astronomer and a productive author of the time. He organized and carried out the first complete enumeration in Tehran with the aid of eight of his students in Darolphonon school in 1867 A. D. He presented the science of statistics and some of the related concepts (such as: Mean) to Iranian for the first time. Also, he was the first to introduce discussions regarding population issues and, specifically, the population theory of Malthus. He drew a comprehensive map of Tehran, prepared tables for matching solar and lunar years, and calculated Iran's formal yearly calendar for 57 years. The latter was A. Zanjani, the translator of Taharatol-Araq by Ebne-Moskoviah (who lived about six centuries before Malthus but had ideas similar to his own). While providing about some of the main population issues including: earths limits for increasing population, law average life expectancy of the Iranians and the considerable reduction of the Iran’s population at the time, compared with attempts of European countries to improve the people health situation which has led to the increase of average life expectancy.