The invention relates to a method of manufacturing a sandwich panel having an asymmetrical configuration in the thickness direction. This method comprises the steps of: a) providing a plate shaped assembly of a first cover part and a second cover part and between a core part of a thermoplastic material containing a suitable blowing agent, wherein the second cover part is not equal to the first cover part regarding heat transfer properties; b) heating the assembly under pressure between press tools in a press, thereby adhering the foamed core part to the first and second cover parts; c) foamingof the thermoplastic material in the core part under pressure between press tools in the press and at a foaming temperature by increasing the spacing between the press tools in a controlled manner; d) cooling the foamed sandwich panel under pressure between the press tools; e) removing the thus cooled sandwich panel from the press; and optionally f) drying the sandwich panel; wherein during stepa) a first compensation part conforming to the heat transfer properties of the second cover part is positioned at the side of the first cover part and/or a second compensation part conforming to the heat transfer properties of the first cover part is positioned at the side of the second cover part, and wherein during or after step e) the first and/or second compensation parts are removed from thesandwich panel.