The invention relates to the use of a peptide which binds to lipopolysaccharide (LPS) or lipoteichoic acid (LTA), for manufacturing a pharmaceutical composition for treating sepsis or septic shock, wherein the peptide comprises the amino acid sequence of apolipoprotein CI (apoCI) or a part thereof that comprises at least the amino acids of the C-terminal helix of apoCI. The use of human apoCI is preferred. The peptide can be administered clinically to patients who have sepsis or threaten to develop sepsis. Measurement of the apoCI content in blood can be utilized for determining the severity and prognosis of the course of the septic condition or for monitoring an anti-sepsis treatment.