A process for removing viruses in fibrinogen solutions and fibrinogen obtained thereof wherein the process starts with an adjusted purified fibrinogen solution, the adjusted purified solution is frozen and then thawed at a temperature between 5 and 20.degree. C., the undissolved materials associated with the fibrinogen are subsequently separated, the temperature is adjusted and the resultant solution is finally subjected to nanofiltration using filters having a pore size smaller than 35 nm.