Abstract This study was designed to examine observer variations in radiographic interpretations of periapical conditions after endodontic therapy and when assessing the quality of the seal of root canal fillings. Radiographs of 90 teeth with 143 roots and 160 root canals, sampled at random from endodontically treated teeth, were evaluated by 9 dentists (3 endodontist, 3 oral radiologists, 3 general practitioners). Film interpretations were made independently by each observer and they were asked to complete pre-designed forms where the criteria for the interpretation were noted. Nine weeks later the same radiographs were evaluated by 2 pairs of examiners, each pair consisting of 1 endodontist and 1 general practitioner. Complete agreement among all 9 individual observers was found in 38% of cases for the periapical conditions and in 41% for the quality of the seal. The corresponding figures for the pairs of examiners were 65%, and 57%, respectively.