Objective: We compared the number of interstitial cells (ICs), nerves, presence of fibrosis and inflammation at the level of full-thickness human ureteropelvic junction (UPJ) tissues obtained from normal subjects, and patients with UPJ obstruction with and without crossing vessels.Material and methods: Normal UPJ tissues (n=12) histopathologically confirmed to be without tumor involvement were obtained from subjects who underwent radical nephrectomy for kidney mass. Additional UPJ tissues were obtained from patients who underwent pyeloplasty due to UPJ obstruction. Crossing vessel was identified in 17 patients. In 57 patients, no crossing-vessel was noted. ICs were stained immunohisto-chemically with anti–human CD117 (c–kit) antibody. Neural tissue was stained with S-100. The numbers of ICs and neurons were compared between the groups: controls with normal UPJ (Group I), Ureteropelvic junction obtruction (UPJO) with crossing vessel (Group II) and UPJ obstruction without crossing vessel (Group III). Groups were also compared in terms of the presence of fibrosis and inflammation.Results: The mean age of total population included in the study was 30.5±18.5 years. No significant dif-ferences were detected between the three groups regarding mean and median numbers of ICs at the level of UPJ (lamina propria and muscle layer) and mean and median numbers of neurons at the level of lamina propria (p>0.05). Likewise, no significant differences were detected between the three groups regarding the presence of fibrosis and inflammation (p>0.05).Conclusion: Number of ICs, neurons, presence of fibrosis and inflammation seem to be similar in the intactUPJ and UPJ with obstruction with and without crossing vessel. Cellular function rather than the numberICs might play a role that warrants further research.