Chronic unilateral primary haematuria is rare and raises difficult problems of diagnosis and treatment as most of the knowledge in this field has been based on a very limited number of patients. This clinical entity needs critical reevaluation as recent progress in endourological investigations has revealed that lesions other than the classical submucosal haemangioma are just as frequently responsible for unilateral primary haematuria. These endoscopic lesions have generally been poorly defined up to now and our data based on a retrospective review of 8 patients emphasises the persistent gaps in our understanding of the pathophysiology of this disease. Among the lesions responsible for unilateral primary haematuria, diffuse petachiae of the renal pelvis and cavities represent the most frequent endoscopic lesion described in our experience (50% of cases). Histologically, these diffuse lesions correspond to non-specific pyelitis, consisting of simple oedema of the lamina propria. In addition to its diagnostic role, endoscopy can also be used to effectively treat the lesions responsible for unilateral primary haematuria, using either electrocoagulation or nitrate cautery, provided a retrograde approach can be completed by a percutaneous approach, with an overall success rate of 75% of cases with a mean follow-up of 16 months.