The aim of this study was to investigate whether systematic differences in solar UV exposure on a specific anatomical site (chest) exist among three groups of Italian sunbathers: healthy subjects (suntanned and non-suntanned individuals) and subjects affected by abnormally high sensitivity to solar exposure. A second aim of the study was to search for a possible relation among biological markers of individual response to UV exposure (such as skin colorimetric parameters, skin temperature and changes in free radical amounts [FR] in the blood) and photosensitivity. FR in the blood were analyzed because of their possible influence on UV carcinogenesis. Measurements of ambient doses (i.e. incident erythemally weighted irradiance on a horizontal surface over a specified period of time) and erythemally effective UV dose received by an anatomical site (here called personal dose or exposure on a specific anatomical site) were investigated. Personal doses received by the chest were determined using polysulfone dosimetry. Exposure Ratio (ER), defined as the ratio between the personal dose and the corresponding ambient dose during the same exposure period, was then calculated. Measuring of skin color in the Commission Internationale de l'Eclairage L (luminance), a (redness), b (yellowness) system and skin temperature were also carried out on the inner upper arm (nonexposed skin site) and on the chest. It was found that the median value of ER was 0.20 (min: 0.09 and max: 0.34) for suntanned individuals, it was 0.17 (min: 0.13 and max: 0.42) for non-suntanned individuals and it was 0.19 (min: 0.14 and max: 0.34) for photosensitive individuals. There were no significant differences across the groups in their median ER scores. In addition, the statistical analysis showed that L on the exposed site before exposure demonstrated consistently higher median scores after exposure in all groups. The b value after exposure was significantly lower than before exposure in all participants, while no significant differences for a were observed before or after exposure between or within the groups. Our findings suggest that photodermatoses are not significantly related to ER and to the changes in biological markers due to too short-term UV exposure.