MicroRNAs (miRs) carried in exosomes serve an important role in the pre‑metastatic microenvironment and in intercellular interactions. However, the function of exosomal‑miR‑10a derived from primary colorectal cancer (CRC) cells on fibroblasts in the lung metastatic micro‑ environment of patients with CRC remains unclear. Reverse transcription‑quantitative PCR was performed using samples from patients with CRC, and demonstrated that the expres‑ sion levels of miR‑10a were significantly lower in serum and cancer tissue samples from patients with CRC compared with in serum from healthy individuals and paired non‑cancerous tissues, respectively. In addition, the expression levels of miR‑10a were inversely associated with the invasion depth of CRC. Exosomal‑miR‑10a derived from CRC cells reduced the proliferative and migratory activities of primary normal human lung fibroblasts (NHLFs), and the expression levels of IL‑6, IL‑8 and IL‑1β in NHLFs. The present study provided insight into the phenotypic alterations of NHLFs induced by exosomal‑miR‑10a derived from CRC cells, which may aid understanding of the mechanism underlying the process of CRC lung metastasis.