Use of lasers in dentistry dates back 20 years but is still not fully exploited, especially when concerning the hard dental tissues. Over the past many efforts and actions have been involved in testing and developing new methods for caries diagnosis. The implementation of these methods in general dental practice is unfortunately still limited because too little scientific evidence exists to support them. One of the age-old concerns for dentists is that decay is often discovered too late. Dentists commonly use x-ray imaging for early caries detection, but this method cannot reveal decay at a sufficiently early stage to avoid restorative methods. Generally, if a caries lesion si detected by x-ray, the mineral loss within the tooth is normally very high and will need invasive treatment. Several laser based techniques, as also other optical methods of detecting caries lesions at an early stage seem to be very promising. Fluorescence of tooth structure is observed when hard tissues are illuminated using laser light. Decayed areas appear dark and provide a contrast against the healthy background surrounding them, so discriminating sound and carious tissues. The aim of this study was to present the possibilities of using laser induced fluorescence in the diagnosis of early caries lesions. The current state-of-the-art is presented, as well as results of our investigations. In our studies an argon ion laser was used to illuminate the teeth and the fluorescence pictures were captured with a CCD camera and then analyzed. Results confirmed that laser induced fluorescence can be used as a sensitive method of caries diagnosis.