This paper will explore the role of astronomy in ancient Mesopotamian medicine. In particular I will discuss a group of texts from the last four centuries BC which relate days in the year, signs of the zodiac, and the ingredients used in preparing medical remedies. Several of these texts rely upon numerical schemes based upon a simple model for the motion of the moon. In this paper I will focus on two questions: (i) the relationship between the mathematical schemes found in these texts and other lunar models in Babylonian astronomy, and (ii) whether these texts were purely theoretical explorations or were used in actual medical practice.