In this talk, we will discuss what information about an entire function may be recovered from measurements of its magnitude on different subsets of the complex plane. This phase retrieval problem for entire functions plays a decisive role in many contemporary works on the recovery of signals from magnitude-only measurements. We will present the theory for the phase retrieval of entire functions starting with some basic observations. We will then discuss Mc Donald's characterisation of entire functions whose magnitudes agree on a single line in the complex plane and, finally, propose some extensions to situations in which magnitude information on two or more lines is available.