<正> The changes of 8 oncogenes and 2 oncosuppressor genes in the specimens of cancer-ous and juxtacancerous tissues of 42 cases of gastric cancer were studied with southern blot hy-bridization and PCR-RFLP method.The probes used were c-Ha-ras

K-ras

N-ras

N-myc

c-myc

hst

EGFR

c-erbB-2

p53 and Rb.Amplification

rearrangement and deletion of c-Ha-ras were detected in 8/33 （24.2%） cases of gastric cancer

amplification or rearrangement ofhst and c-erbB-2 in 11/42 （26.2%） and 12/41 （29.2%） cases respectively

amplification ofEGFR in 9/42 （21.4%） cases

and deletion or rearrangement of p53 and Rb in 9/30 （30.0%）and 2/15 （13.3%） cases respectively.Amplification or rearrangement of N-ras （0/33）

K-ras（1/26）

N-myc （1/26）

and c-myc （1/35）was rarely encountered.These findings suggest thatc-Ha-ras

hst

c-erbB-2

EGFR and p53 may be important genes involved in the pathogenesisof gastric cancer.