During recent decades, the duties and care rendered by Swedish dental hygienists have continuously expanded, and since 1991 they are licensed to practice dental hygiene independently. The aim of the present study was to investigate the accuracy of dental hygienists in examining and recording dental caries in comparison with dentists performing identical examinations. The study included two parts: A) Registration of carious lesions from radiographs of 100 extracted teeth, where the correct diagnosis could be verified, and B) clinical examination and registration of carious lesions in 213 patients. No statistically significant differences could be found between the dental hygienists' and their control dentists' accuracy to diagnose and record dental decay, with the exception of the number of initial lesions (white spot lesions) registered clinically, where the dental hygienists recorded more buccal and lingual lesions. Irrespective of the group of examiners (dental hygienists or dentists), however, the inter-examiner variation was wide. The variation decreased with the size of the lesion and increased with the age of the patient. This study suggests that no patient with a restorative treatment need would have been neglected if the dental hygienists had performed the examination, and, possibly, a more accurate non-restorative treatment need would have been addressed.