The kinetics of serum beta-carotene loading were evaluated to help determine the minimum time required to load fatty tissues, including atherosclerotic plaque and skin, with beta-carotene. Loading atherosclerotic plaque with yellow beta-carotene pigment increases absorption of blue laser radiation, potentially enhancing the selectivity and quality of laser angioplasty. Five healthy volunteers received 300 mg beta-carotene daily (the maximum FDA recommended dose) for 21 days in three divided doses with meals. Serum total carotenoid levels increased exponentially with a 10-day time constant from an average of 1.7-6.5 micrograms/ml (p less than 10(-4]. The skin began to yellow visibly at 10 days and became increasingly yellow for several weeks thereafter, suggesting that augmenting the yellow color of fatty tissues and atherosclerotic plaque with oral beta-carotene may require a minimum of several weeks to attain the maximum effect.