Documented astronomical observations such as the heliacal rising and setting of stars and planets, eclipses or the first and last visibility of the lunar crescent can be used to establish absolute dates for ancient societies. Frequently utilised in earlier times, the usefulness of ancient astronomical observations for dating purposes was questioned and even rejected during the last thirty years. Referring to preserved data from ancient Egypt and Mesopotamia from the second millennium BCE the potential of different sets of astronomical data as well as the uncertainties and possible pitfalls of this dating method will be discussed.