Objective: To examine whether lipoxin A4 (LXA4) induces apoptosis of renal interstitial fibroblasts and explore the mechanisms of signal pathway of LXA4. Methods: Rat renal interstitial fibroblasts (NRK-49F cells) were exposed to LXA4 at different concentrations. Prior to the experiment, the cells were transfected with Smac or calpain 10 antisense oligodeoxynucleotide (ODN), or treated with calcium channel inhibitor SK&F96365. Apoptosis of cells was recognized by double staining using acridine orange and ethidium bromide, observed in laser scanning confocal microscope, and counted by a flow cytometer. Caspase-3 activities were measured by colorimetric assay. The levels of free cytosolic calcium ([Ca2+ ]i) were analyzed in fura-2-loaded cells by laser scanning confocal microscopy. Expression of calpain 10 mRNA was determined by RT-PCR. Expressions of Smac protein and threonine phosphorylated Akt1 proteins at 308 site were determined by a Western blotting analysis. Activity of signal transducers and activators of transcription-3 (STAT3) was determined by electrophoretic mobility shift assay. Results: LXA4 at the concentrations of 0.1 and 1μmol/L induced 9.83% and 33.82% apoptosis of NRK-49F cells respectively, reduced at S and G2-M phase and increased the cells at G0-G1 phase in a dose-dependent manner. Treatment of the cells with LXA4 increased the expressions of calpain 10 and Smac, the levels of [Ca2+ ]i and activity of caspase-3. It also down-regulated the DNA-binding activity of STAT3 and expression of threonine phosphorylated Akt1. Transfection of the cells with calpain 10 antisense ODN inhibited the LXA4-induced apoptosis, activity of caspase-3 and expression of calpain 10, and ameliorated the decreased activity of STAT3. Transfection of the cells with Smac antisense ODN inhibited the LXA4-induced apoptosis, activity of caspase-3 and expression of Smac. Pretreatment of the cells with SK & F96365 inhibited the LXA4-induced apoptosis, levels of [Ca2+ ]i, expression of calpain 10 and Smac. Conclusion: LXA4 at high concentration induced apoptosis of rat renal interstitial fibroblasts via [ Ca2 + ] i-dependent up-regulation of calpain 10 and Smac expressions.