Lung cancer is the leading cause of cancer-associated mortality worldwide, although molecular imaging techniques, including fludeoxyglucose positron emission tomography, have markedly improved the diagnosis of lung cancer. HIWI is a member of the human piwi family, members of which are known for their roles in RNA silencing. HIWI has been shown to serve a crucial function in stem cell self-renewal, and previous studies have reported HIWI overexpression in lung cancers. Furthermore, HIWI has been proposed to regulate the maintenance of cancer stem cell populations in lung cancers. The present study investigated the mRNA and protein expression levels of HIWI in non-small cell lung cancer (NSCLC) specimens harvested from 57 patients, using reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. Subsequently, the HIWI expression level was manipulated using gain-of-function and loss-of-function strategies, and the role of HIWI in the proliferation of human A549 NSCLC cells was investigated using Cell Counting Kit-8 and colony formation assays. The mRNA and protein expression levels of HIWI were significantly upregulated in the intratumor NSCLC specimens, as compared with the peritumor specimens. Furthermore, the mRNA and protein expression levels of HIWI in A549 cells were successfully manipulated using the two strategies. Overexpression and knockout of HIWI were associated with the promotion and inhibition of A549 cell proliferation, respectively. The results of the present study suggested that HIWI is overexpressed in NSCLC tissues and demonstrated that upregulation of HIWI may promote the growth of lung cancer cells; thus suggesting that HIWI may have an oncogenic role in lung cancer.