The impact of DJ tube retention time on renal function has received scant attention from researchers. Nevertheless, there is a plethora of clinical evidence indicating that protracted stent retention can result in renal insufficiency, or even renal atrophy, which can consequently lead to loss of renal function or nephrectomy.A comprehensive review of the medical records of all patients who underwent DJ tube placement between 1 January 2010 and 1 September 2024 in our hospital was performed. Cases with a duration of DJ tube placement exceeding two years were selected for further analysis, as supported by previous studies. The final study population comprised 74 cases with indwelling DJ tubes for a minimum of two years. Renal size/glomerular width (PW) was measured on the basis of CT coronal scanning, and the mean value of PW and the rate of change of PW were calculated before the first placement of the DJ tube and at the last follow-up, respectively. Furthermore, the study recorded eGFR, serum creatinine (Scr), blood urea nitrogen (BUN), and blood uric acid (UA) at two time points: before and after DJ tube placement. The mean duration of indwelling DJ tubes was 67.94 ± 48.26 months in the unilateral DJ tube indwelling group (including isolated kidney cases) and 50.22 ± 29.65 months in the bilateral group. During the mean retention time of 67.94 ± 48.26 months, the mean PW change rates of unilateral DJ tube stented kidneys and healthy kidneys/unilateral kidneys were - 39.01 ± 26.1% and 16.52 ± 25.4%, respectively, which were statistically significant (P < 0.01). The mean rate of change in PW in the left and right sides of the bilateral DJ tube retention group was - 18.31 ± 36.3% over a mean retention time of 50.22 ± 29.65 months, which was statistically significant (P < 0.01). Furthermore, a statistically significant decrease of -37.81 ± 51.2% in eGFR was observed before and after bilateral DJ tube placement (P < 0.01). No statistically significant difference (P > 0.05) was observed in eGFR in the unilateral DJ tube placement group (including isolated kidney cases) and in Scr, BUN, and UA values in the unilateral and bilateral DJ tube placement groups before and after DJ tube placement. In the unilateral DJ tube-placement group, the duration of DJ tube placement exhibited a negative correlation with the rate of change in mean PW percentage (Pearson correlation coefficient r = -0.470, P = 0.002) and a positive correlation with the rate of change in eGFR (Pearson correlation coefficient r = 0.653, P < 0.01). Conversely, in the bilateral DJ tube retention group, DJ tube retention duration exhibited no significant correlation with the change in mean percentage of PW.However, it demonstrated a negative correlation with the rate of change in eGFR (Pearson correlation coefficient r = -0.443, P = 0.03). In patients with unilateral or bilateral indwelling DJ tubes, renal size may decrease over time despite the presence of an indwelling DJ tube, especially in patients with bilateral indwelling DJ tubes.