A pharmaceutical composition comprising a conjugate of a therapeutic agent or imaging agent and a polysaccharide preparation, wherein: the therapeutic or imaging agent is selected from a radioactive agent, a fluorescent agent, a cytotoxic agent, a tyrosine kinase inhibitor, a proteasome inhibitor, a protease inhibitor, an anti-angiogenic agent, an anti-metastatic agent, a steroid, a biologic immunomodulator, a monoclonal antibody, an antibody fragment, an aptamer, an siRNA, an antisense molecule, a fusion protein, a cytokine, a cytokine receptor, a bronchodialator, a statin, an anti-inflammatory agent, a microtubule inhibitor, a topoisomerase inhibitor, an antimetabolite, a protein synthesis and degradation inhibitor, a mitotic inhibitor, an alkylating agent, a platinating agent, an inhibitor of nucleic acid synthesis, a histone deacetylase and DNA methyltransferase inhibitor, a nitrogen mustard, a nitrosourea, an ethylenimine, an alkyl sulfonate, a triazene, a folate analog, a nucleoside analog, a ribonucleotide reductase inhibitor, a vinca alkaloid, a taxane, an epothilone, an intercalating agent, a signal transduction inhibitor, an apoptosis inducer, a cytokine, a chemokine, and a vaccine; and the polysaccharide preparation has the following characteristics: a weight average chain molecular weight between 3,500 and 8,000 Da; anti-Xa activity and anti-IIa activity each less than 50 IU/mg; and greater than 5% and less than 50% glycol split uronic acid residues; and wherein the polysaccharide preparation comprises polysaccharides of the Formula I: [U w -H x,y,z] m ∼[U G -H x,y,z] n wherein each occurrence of U indicates a uronic acid residue and each occurrence of H indicates a hexosamine residue; wherein m and n are integers such that m = 4-16, and n = 1-4; each of w, x, y and z can independently be the same or different for each occurrence of [U w -H x,y,z] and each of x, y and z can independently be the same or different for each occurrence of [U G -H x,y,z], wherein w = -2OS or -2OH; x = -NS or -NAc; y = -3OS or -3OH; z = -6OS or -6OH; and wherein the symbol ∼ indicates that the units marked m and n are distributed along the polysaccharide chain and are not necessarily in sequence. the therapeutic or imaging agent is selected from a radioactive agent, a fluorescent agent, a cytotoxic agent, a tyrosine kinase inhibitor, a proteasome inhibitor, a protease inhibitor, an anti-angiogenic agent, an anti-metastatic agent, a steroid, a biologic immunomodulator, a monoclonal antibody, an antibody fragment, an aptamer, an siRNA, an antisense molecule, a fusion protein, a cytokine, a cytokine receptor, a bronchodialator, a statin, an anti-inflammatory agent, a microtubule inhibitor, a topoisomerase inhibitor, an antimetabolite, a protein synthesis and degradation inhibitor, a mitotic inhibitor, an alkylating agent, a platinating agent, an inhibitor of nucleic acid synthesis, a histone deacetylase and DNA methyltransferase inhibitor, a nitrogen mustard, a nitrosourea, an ethylenimine, an alkyl sulfonate, a triazene, a folate analog, a nucleoside analog, a ribonucleotide reductase inhibitor, a vinca alkaloid, a taxane, an epothilone, an intercalating agent, a signal transduction inhibitor, an apoptosis inducer, a cytokine, a chemokine, and a vaccine; and the polysaccharide preparation has the following characteristics: a weight average chain molecular weight between 3,500 and 8,000 Da; anti-Xa activity and anti-IIa activity each less than 50 IU/mg; and greater than 5% and less than 50% glycol split uronic acid residues; and wherein the polysaccharide preparation comprises polysaccharides of the Formula I: [U w -H x,y,z] m ∼[U G -H x,y,z] n wherein each occurrence of U indicates a uronic acid residue and each occurrence of H indicates a hexosamine residue; wherein m and n are integers such that m = 4-16, and n = 1-4; each of w, x, y and z can independently be the same or different for each occurrence of [U w -H x,y,z] and each of x, y and z can independently be the same or different for each occurrence of [U G -H x,y,z], wherein w = -2OS or -2OH; x = -NS or -NAc; y = -3OS or -3OH; z = -6OS or -6OH; and wherein the symbol ∼ indicates that the units marked m and n are distributed along the polysaccharide chain and are not necessarily in sequence. a weight average chain molecular weight between 3,500 and 8,000 Da; anti-Xa activity and anti-IIa activity each less than 50 IU/mg; and greater than 5% and less than 50% glycol split uronic acid residues; and wherein the polysaccharide preparation comprises polysaccharides of the Formula I: [U w -H x,y,z] m ∼[U G -H x,y,z] n wherein each occurrence of U indicates a uronic acid residue and each occurrence of H indicates a hexosamine residue; wherein m and n are integers such that m = 4-16, and n = 1-4; wherein each occurrence of U indicates a uronic acid residue and each occurrence of H indicates a hexosamine residue; wherein m and n are integers such that m = 4-16, and n = 1-4; each of w, x, y and z can independently be the same or different for each occurrence of [U w -H x,y,z] and each of x, y and z can independently be the same or different for each occurrence of [U G -H x,y,z], wherein w = -2OS or -2OH; x = -NS or -NAc; y = -3OS or -3OH; z = -6OS or -6OH; and wherein the symbol ∼ indicates that the units marked m and n are distributed along the polysaccharide chain and are not necessarily in sequence.