Pulsed field gel electrophoresis and Southern blot analysis showed that the human oncogenes, HST1 and INT2, which code for proteins homologous to fibroblast growth factors, are less than 45 kb apart on the long arm of chromosome 11. Moreover, analysis of two overlapping cosmid clones, one containing INT2 and the other HST1 sequences, showed that HST1 is located about 35 kb downstream of INT2 in the same transcriptional orientation. The observed close proximity of the INT2 and HST1 genes may provide important insight on the origin and regulation of expression of these related genes.