NOVELTY - A membrane comprising nanosized pores is produced by providing support or membrane forming material comprising first and a second opposite side; depositing film of membrane material or protective material on the colloidal particles and support or membrane forming material; and forming window in support throughout thickness of the support with respect to perforated membrane to reveal membrane from second side of support; or etching membrane forming material through perforations in protective material so that a perforated membrane is formed.    USE - Method for producing membrane comprising nanosized pores used in biosensors and drug delivery systems; sieving, separation and purification of small molecules and biomolecules; filtering of gases and liquids; low temperature sterilization of fluids; and fuel cell membranes.    ADVANTAGE - The method produces nanosize pores in short time and on a large scale without the use of expensive equipment. The nanopore membranes have narrow size distribution and are randomly arranged. The inter-pore distance shows very little variation.    DETAILED DESCRIPTION - The membrane comprising nanosized pores is produced by:    (A) providing support or membrane forming material comprising first and a second opposite side;    (B) depositing and adsorbing colloidal particles on first side of support or membrane forming material;    (C) depositing film of membrane material or protective material on the colloidal particles and support or membrane forming material;    (D) applying adhesive material onto colloidal particles covered by membrane forming film or protective material;    (E) mechanically removing covered colloidal particles from support or membrane forming material by peeling off adhesive material together with colloidal particles, where at least part of membrane forming film or protective material film covering colloidal particles is removed from support or membrane forming material, while perforated membrane forming film or perforated protective material remains on support or membrane forming material; and    (F) forming window in support throughout thickness of the support with respect to perforated membrane to reveal membrane from second side of support; or    (G) etching membrane forming material through perforations in protective material so that a perforated membrane is formed.    An INDEPENDENT CLAIM is included for a membrane produced by above method.