A vaccine is disclosed which is useful for protecting a host from Gram negative infections and the effects of endotoxin, therefore preventing sepsis and septic shock. The vaccine is prepared by combining LPS free or in conjugate form with a stoichiometric excess of a peptide of the formula:

(a) (A)_n wherein A is Lysine or Arginine and n is an integer with a minimum value of 7;

(b) (AB)_m wherein A is Lysine or Arginine and B is a hydrophobic amino acid selected from the group consisting of Valine, Leucine, Isoleucine, Tyrosine, Phenylalanine and Tryptophan; m is an integer with a minimum value of 3; and

(c) (ABC)_p wherein A is a cationic amino acid which is Lysine or Arginine; B and C are hydrophobic amino acids which may be the same or different and are selected from the group consisting of Valine, Leucine, Isoleucine, Tyrosine, Phenylalanine and Tryptophan; p is an integer with a minimum value of 2.