Background: Bladder catheterization is one of the most frequent procedures in Urology, but it is not exempt from complications.
 Relevance: Unintentional Foley catheter placement in the ureter is a rare occurrence that can produce serious complications. Few cases are described in the literature.
 Case report: We present herein two cases of inadvertent Foley catheter balloon inflation in the ureter. Case 1: an 85-year-old-patient with an indwelling Foley catheter was admitted to our emergency department due to abdominal pain in the hypogastrium, dysuria, and diagnosis of septic shock from extended-spectrum beta-lactamase-producing Escherichia coli. Case 2: a 75-year-old patient underwent transurethral resection of the bladder and presented with persistent hematuria and abdominal pain in the postoperative period.
 Conclusion: Unintentional urinary catheter placement in the ureter is an unusual complication and a diagnostic challenge that should be suspected in the presence of abdominal pain after bladder catheterization.