RESUMEN
Balkan Endemic Nephropathy (BEN) is a non-inflammatory, slowly progressing, familial, primarily tubulo-interstitial, bilateral renal disease that affects rural populations in several Balkan countries. Our study describes a time trend of the incidence of BEN in eight villages of Vratza District, Bulgaria, for the period 1965-1987, based on three various data sets. The data suggest that after the initial peak between 1967 and 1970, the incidence remained quite stable for the period 1970-1984, and declined after 1984. However, the study also demonstrates under-recording of BEN cases and less complete case identification, especially after 1979. Migration of population might also have contributed to an apparent decline in registered cases. We detected cases of BEN in villages that previously were BEN-free. We recommended a rigorous monitoring of BEN in all afflicted countries, before concluding that the incidence of BEN is decreasing.