Radiological technique in the investigation of the lacrimal system has greatly benefited from various advances in radiology; techniques of catheterisation, contrast media, seriography, subtractions, associated complex tomography (dacryocystotomography), tomodensitometry. To these may be added the dynamic nature of isotope studies (cinegammadacrycystography). These different techniques may be used in the precise analysis of the morphology of the lacrimal system, from the canaliculi to the meatuses. After reviewing normal radiological anatomy, the authors describe morphological abnormalities, according to different forms of obstruction, according to their site. This morphological discovery requires possible changes in technique (additional tomography, for example). The quality of the preoperative morphological exploration influences the quality of the therapeutic results obtained.