The first major Iranian dynasty Achaemenid (550 BC) promoted the development of culture and science extensively. The great scholars such as the philosopher Heraclitus of Ephesus, the Babylonian astronomer Kidinnu and even the historian Herodotus were Persian subjects. The ancient cultures of the Egyptians, Babylonians, Elamites, and others continued to exist and develop. Babylonian Physicians were all over the territories and served all people including Persians. Xenophon relates that when the Greek soldiers who served under Cyrus the younger passed through the territory of Babylonia, they found sufficient number of Physicians even in the villages to treat the wounded warriors. Texts describe how physicians used medicine, prayers and magic, they would often model images of evil spirits out of clay and shatter them, in order to restore the invalid to health.

Achaemenid made Babylon one of their major capitals and extensively used the texts at the temple libraries. The library and museum at the Persepolis was build to rival the Babylonian archives famous in the ancient world. Greek and Egyptian physicians were invited to join the Achaemenid court and served the royal household. Persians also adopted the tradition of paying the physicians according to the rank and gender. The archives at Persepolis indicate that physicians and midwives who delivered boys were paid double the amount they got when the baby delivered was a girl. The records do not indicate severe punishments if the sick person died, as was the case under Hammurabi. Texts also show lists of plants, herbs and other substances used for medicinal purposes. Drugs are taken internally; mercury, antimony, arsenic, sulfur and animal fats are also prescribed. All are basically the same as Babylonian medicine and prescriptions.

At one point Darius orders a representative to return to Egypt in order to restore the department of the ruined house of life dealing with medicine; " While his majesty was in Elam he ordered me (Udjahorresne) to return to Egypt. I gave them every useful thing and all their instruments indicated by the writings, as they had been before. His majesty did this because he knew the virtue of this art to make every sick man recover". The subsequent Seleucid and Parthian dynasties followed the same trends with more Greek influence science and art due to massive presence of Greeks in the area. However the flourishing of science and technology happened in the Sassanian period with major centers of learning and the famous university Jundaishapur.
The Sassanian king, Khosrow Anoshirvan is mentioned by many historians and biographers to have been a major promoter of all sciences including philosophy and medicine. In a Pahlavi text (Karnamag) he is quoted the following; "We have made inquiries about the rules of the inhabitants of the Roman Empire and the Indian states. We have never rejected anybody because of their different religion or origin. We have not jealously kept away from them what we affirm. And at the same time we have not disdained to learn what they stand for. For it is a fact that to have knowledge of the truth and of sciences and to study them is the highest thing with which a king can adorn himself. And the most disgraceful thing for kings is to disdain learning and be ashamed of exploring the sciences. He who does not learn is not wise".

History of ancient Medicine in Mesopotamia & Iran