We present the first results from our HST-ACS survey of the nearby galaxy M81. These data provide the deepest and most detailed picture of the stellar populations in this prototypical spiral galaxy, allowing to study in detail its spatially resolved star-formation history. In combination with deep Chandra observations allow us to classify the X-ray sources and study their link with the star-formation history of the galaxy. In this presentation we will discuss the analysis of the HST data, the derivation of the colour-magnitude and colour-colour diagrams and we will present preliminary results on the stellar populations of different regions of M81.