The subject of the invention is a method for making an in vitro prognosis of severity for a patient in septic shock, including the following steps: (i) the level of expression of the expression product of at least one gene chosen from the lilrb2 and lilrb1 genes is measured in vitro on the basis of a biological sample taken from the patient, (ii) the level of expression of the expression product of the at least one gene is compared with a control level of expression, of the expression product of the same gene, with a good prognosis of severity, in which a level of expression of the expression product of the at least one gene below the control level of expression indicates a poor prognosis of severity for the patient, and also a kit for implementing the method.