We examined microRNA (miRNA)-10b expression in peripheral blood mononuclear cells (PBMCs) of nonsmall-cell lung cancer (NSCLC) patients for its clinical value. A group of 74 patients confirmed with NSCLC were recruited as case group and 52 healthy volunteers as control group. PBMCs were isolated from all subjects, and miRNA-10b expression level in these cells was measured by reverse transcription quantitative real-time polymerase chain reaction (qRT-PCR). The correlation between miRNA-10b expression levels and the clinical and pathological characteristics of NSCLC was obtained. The miRNA-10b expression level in NSCLS patients is markedly higher than control subjects (P < 0.01). Analysis of receiver operating characteristic (ROC) curve estimated the peak diagnostic sensitivity of miRNA-10b at 86.5 % and specificity at 76.9 %. NSCLC patients were divided into high expression group (64 patients) and low expression group (10 patients). Further analysis showed that miRNA-10b expression levels in PBMCs correlated with lymph node metastasis, distant metastasis, and TNM classification (all P < 0.05). The 5-year survival rate in high expression group was significantly lower than low expression group (P = 0.017). Multivariate analysis by Cox regression model showed that high miRNA-10b expression, age > 60 years, lymph node and distant metastases, and stage III-IV carcinoma were risk factors for poor prognosis in NSCLC patients (all P < 0.05). MiRNA-10b expression levels in PBMCs can distinguish NSCLC patients from cancer-free subjects with a high sensitivity and specificity, suggesting that miRNA-10b expression in PBMCs is a valuable diagnostic and prognostic marker in NSCLC.