We have identified three novel, rarely expressed human genes that encode new members of the lipid transfer/lipopolysaccharide binding protein (LT/LBP) gene family based on sequence homology. BPI and other members of the LT/LBP family are structurally related proteins capable of binding phospholipids and lipopolysaccharides. Real-time PCR studies indicate that BPIL1 and BPIL3 are highly expressed in hypertrophic tonsils. In situ hybridization analysis of BPIL2 shows prominent expression in skin specimens from psoriasis patients. BPIL1 and BPIL3 map to Chromosome 20q11; thus, these novel genes form a cluster with BPI and two other members of the LT/LBP gene family on the long arm of human Chr 20. BPIL2maps to Chr 22q13. The exon/intron organization of all three genes is highly conserved with that of BPI, suggesting evolution from a common ancestor.