The authors evaluated objective measurements of constitutive skin color and ultraviolet light sensitivity in relation to risk of cutaneous malignant melanoma (CMM). Incident CMM cases (n = 183) were diagnosed between December 1994 and January 1999 at the Maurizio Bufalini Hospital in Cesena, Italy. Controls (n = 179) were mostly spouses/partners of cases and were frequency-matched by age and sex. In addition to interviews, constitutive skin color and skin ultraviolet light sensitivity were assessed by colorimetry and minimal erythema dose (MED), respectively. Odds ratios were estimated using unconditional logistic regression. The odds of CMM increased by a factor of 1.20 (95 percent confidence interval: 1.12, 1.30) for each unit of skin brightness and by a factor of 1.24 (95 percent confidence interval: 1.07, 1.43) per 10 mJ/cm(2) of MED. These associations were largely independent of phenotypic or sun-related characteristics and were modified by sun exposure. Increased risk of CMM was observed only among subjects with the highest levels of sun exposure. Epidemiologic studies of CMM may benefit from the inclusion of colorimetric and MED measurements along with traditional risk factors to obtain more accurate, quantitative, and objective information.