The efficacies of chemotherapeutic agents are often limited by side effects and acquired drug resistance. We have investigated whether the differential expression pattern of 14-3-3 sigma affects cisplatin response in non-small cell lung cancer cell lines. Two pairs of parental/cisplatin resistant cell lines (A549/CRA549 and Calu1/CR-Calu1) and clinical lung cancer biopsy samples were analysed for 14-3-3 sigma expression. Cell viability was assessed by WST assay; and 14-3-3 sigma expression was suppressed by siRNA transfection. 14-3-3 sigma mRNA expression increased in CR-A549 and CR-Calu1 compared with their cisplatin-sensitive parental A549 and Calu1 cell lines. But when 14-3-3 sigma expression was suppressed, elevated cisplatin response was seen in A549 and CR-Calu1 cell lines. Increased 14-3-3 sigma expression might also account for reduced cisplatin response in vivo, since, 14-3-3 sigma expression in clinical biopsy samples obtained from lung cancer patients undergoing cisplatin-based chemotherapy significantly higher in the non-responder compared with the responder group. We therefore propose that increased 14-3-3 sigma expression is correlated with cisplatin response in non-small cell lung cancer cells; monitoring its expression might become useful in the future in predicting poor outcome to cisplatin treatment and/or the verification of acquired cisplatin resistance in lung cancer patients.