The lacrimal drainage systems of 78 eyes were studied by technetium scanning at the University of Iowa and, of these, 25 were also subjected to conventional contrast dacryocystography. Twenty-six eyes were asymptomatic for epiphora and normal scans were recorded on all of them. All of the remaining 52 symptomatic eyes had an abnormal lacrimal scan with either a presac or a postsac blockage. In general, there was good correlation with dacryocystography, with the exception of three cases of functional block which had a normal dacryocystogram. Technetium scanning should serve as a valuable tool for diagnosing and localizing lacrimal obstruction.