The aim of this study is to investigate the clinical significance of the ratio between interleukin‐17 (IL‐17) secreting cell and FOXP3‐positive regulatory T cell (FOXP3⁺ Treg) infiltration in renal allograft tissues with acute T‐cell‐mediated rejection (ATCMR). Fifty‐six patients with biopsy‐proven ATCMR were included. Infiltration of FOXP3⁺ Treg and IL‐17‐secreting cells was evaluated with immunostaining for FOXP3 or IL‐17 on the biopsy specimens, and the patients were divided into the FOXP3 high group (Log FOXP3/IL‐17 > 0·45) or the IL‐17 high group (Log FOXP3/IL‐17 < 0·45). We compared the allograft function, severity of tissue injury, and clinical outcome between the two groups. In the IL‐17 high group, allograft function was significantly decreased compared with the FOXP3 high group (P < 0·05). The severity of interstitial and tubular injury in the IL‐17 high group was higher than the FOXP3 high group (P < 0·05). The proportions of steroid‐resistant rejection, incomplete recovery and recurrent ATCMR were higher in the IL‐17 high group than in the FOXP3 high group (all indicators, P < 0·05). The IL‐17 high group showed lower 1‐year (54% versus 90%, P < 0·05) and 5‐year (38% versus 85%, P < 0·05) allograft survival rates compared with the FOXP3 high group. Multivariate analysis revealed that the FOXP3/IL‐17 ratio was a significant predictor for allograft outcome. The FOXP3/IL‐17 ratio is a useful indicator for representing the severity of tissue injury, allograft dysfunction and for predicting the clinical outcome of ATCMR.