Described is a parvovirus formulation which comprises (a) at least 1×109 pfu/ml of parvovirus H1 (H-1PV) or a related rodent parvovirus such as LuIII, Mouse minute virus (MMV), Mouse parvovirus (MPV), Rat minute virus (RMV), Rat parvovirus or Rat virus (RV) and (b) a pharmaceutically acceptable carrier containing 40-50% Iodixanol (w/v), 0.7-0.9 mmol CaCl2×2 H2O, 50-60 mmol NaCl, 0.9-1.2 mmol KCl, 0.7-0.95 mg/ml Tromethamine and 0.05-0.15 mg/ml Edetate calcium disodium. A preferred use is the therapy of a brain tumour by intratumoral injection.