The aim of this investigation was to find out what properties are demanded to give in-plane strength in a hand sheet of newsprint furnish. How different treatments (refining) affect the mechanical and chemical pulps and how they interact according to fracture toughness index was studied. Thermo mechanical pulps from different freeness levels were studied and further beaten in a PFI-mill. Two different chemical pulps beaten in an Escher Wyss-refiner with different edge loads and energy levels were used as reinforcement with various amount. Also addition of starch and press load were varied. Results: * TMP- pulp taken out from the refiner with a lower energy level than usual got increasing fracture toughness with a second beating in the PFI-mill. * The factorial trials with multivariate analysis showed that the most important factors for fracture toughness are the amount of chemical pulp, energy level in beating chemical pulps, fiber length, edge load and coarseness (in that order). Fiber characterization (FiberMaster) gives information more suited to predict the fracture properties than drainage properties.