Long noncoding (Lnc)RNA np_5318 has been proved to be involved in renal injury, while its functionality in renal ischemia‑reperfusion (I/R) injury is unknown. Therefore, the present study aimed to investigate the role of lncRNA np_5318 in the development of renal I/R injury. Renal I/R injury model and I/R cell model were established in vitro. The expression of np_5318 in I/R cell was inhibited by small interfering (si)‑np_5318 and increased by pc‑np_5318. Renal function was detected and evaluated by automatic biochemical tests. Immunohistochemical staining was performed to detect the expression cluster of differentiation (CD)31, transforming growth factor (TGF)‑β1 and (mothers against decapentaplegic homolog 3) Smad3 in renal tissue. The interaction between np_5318 and Smad3 was verified by chromatin immunoprecipitation (ChIP). Western blotting was performed to detect the expression levels of TGF‑β1, Smad3 and phosphorylated (p)‑Smad3 in renal tissue and renal cells. Expression of np_5318 in renal tissue and renal cells was detected by reverse transcription‑quantitative PCR. Relative cell viability was confirmed by MTT assay. Renal function was impaired and pathological changes in renal tissue were observed in the renal I/R injury group, indicating the renal I/R injury model was successfully established. Compared with the sham group, the expression level of np_5318 significantly increased in the renal I/R injury group. ChIP data confirmed the interaction between np_5318 and Smad3. The expression of TGF‑β1, Smad3 and p‑Smad3 in renal tissue was also significantly increased in the renal I/R injury group. Furthermore, the I/R cell model in vitro was successfully constructed and np_5318 in I/R group was significantly increased compared with the control group. Cell growth was significantly suppressed in the I/R group compared with the control group. Additionally, transfection with pc‑np_5318 significantly inhibited cell growth of I/R cells at 48 and 72 h. While inhibition of np_5318 by si‑np_5318 significantly increased the cell growth of I/R cells at 48 and 72 h. Moreover, the level of TGF‑β1, p‑Smad3 and Smad3 was significantly increased in the I/R group compared with the control group, and transfection with pc‑np_5318 significantly increased the level of TGF‑β1, p‑Smad3 and Smad3. While inhibition of np_5318 by si‑np_5318 significantly suppressed the level of TGF‑β1, p‑Smad3 and Smad3.