The aim of this in vitro study was to evaluate the performance of a new laser method (DIAGNOdent, KaVo) by comparing it to the visual inspection, conventional bitewing radiography and digital bitewing radiography. Fifty fresh permanent teeth with clinically sound or suspicious fissures were selected. The teeth were submitted to the diagnostic tests by 2 examiners independently after calibration. The laser examination was repeated to assess the reproducibility. The teeth were sectioned right in the spot that showed the highest value by the laser device. Histological examination of sections (40x magnification) served as gold standard. The results showed that: 1) the intra and interobserver agreement for the DIAGNOdent was excellent (values over 0.87); 2) the sensitivity, specificity and predictive values were very high; 3) and the Spearman correlation coefficient of DIAGNOdent was the best one (R = 0.81), followed by visual inspection (R = 0.68).