Introduction: Ureteropelvic junction obstruction is a pathology typically diagnosed in childhood. Nevertheless, some clinically silent cases may be unnoticed until adulthood. Case description: We report the case of a 53-year-old female with hydronephrosis due to ureteropelvic junction stenosis diagnosed in the adulthood, who subsequently developed obstruction with progressive worsening of renal function without symptoms. Conclusion: The natural history of ureteropelvic junction obstruction is still obscure. Diuretic renogram is the gold standard for diagnosis and follow-up of ureteropelvic junction obstruction, but is weak in predicting the evolution of the disease, especially in patients with vague symptoms. Conservative treatment of adult patient with equivocal ureteropelvic junction obstruction seems reasonable, but requires a close clinical follow-up and strict patient compliance in order to promptly identify significant obstruction.