The bioavailability of carotenoids is the fraction of ingested carotenoids utilized for normal physiological functions or storage, while bioconversion is the proportion of bioavailable carotenoid converted to retinol (vitamin A). Factors influencing carotenoid bioavailability and bioconversion have been incorporated in the mnemonic "SLAMENGHI": species of carotenoid; molecular linkage; amount of carotenoids consumed in a meal; matrix in which the carotenoid is incorporated; effectors of absorption and bioconversion; nutrient status of the host; genetic factors; host-related factors; and mathematical interactions. In this paper, an attempt is made to quantify the impact of the various SLAMENGHI factors on carotenoid bioavailability and bioconversion although many of the data available are not strictly comparable.