The present invention relates to a liquid composition comprising polyclonal immunoglobulins, at least one viscosity modulating amino acid, selected from arginine and histidine, and at least one stabilising amino acid, selected from glycine and proline, wherein more than 90% of the polyclonal immunoglobulins are in the form of monomers or dimers and less than 5% in the form of polymers, and wherein the immunoglobulin concentration in the composition is above 160 g/L and the pH is in the range from 5.2 to 5.9. The invention further relates to a liquid composition for use in medical treatment, to amino acids for formulating a highly concentrated polyclonal immunoglobulins as well as a method of formulating.