Objective To explore the mechanism of the decreased expression of connexin gene (Cx) 43 in human gastric cancer. Methods Detections on mutation of Cx43 coding region in 30 cases of human gastric cancer and control normal tissues were undertaken by means of reverse transcription-polymerase chain reaction-single strand conformation polymorphism (RT-PCR-SSCP). Results [WTBZ]No point mutation of Cx43 was found in 30 cases with human gastric cancer. Conclusion The decreased expression of Cx43 was not related to the mutation of coding region, but to the non-coding sequence, especially the 5' regulation sequence. The results were helpful for the further studying of the relationship between gastric cancer and connexin gene. The RT-PCR-SSCP is effective, fast, inexpensive and radiationless for mutation detection, which may be a means of gene diagnosis for gastric cancer.