Anticancer and antiatherogenic properties of carotenoids have been attributed to their antioxidant effects. However, the antioxidant effect of β-carotene is a controversial topic. There is a great deal of discrepancy betweenin vivoandin vitroactions. One of the major problems ofin vitrostudies using β-carotene is its insolubility in aqueous solutions; this necessitates the use of organic solvents, which drastically limits the use of the solutions in cell culture studies. This paper reports a new method of solubilization of β-carotene in aqueous solution using lyso phosphatidylcholine which permits the preparation of high concentrations of β-carotene. The β-carotene aqueous solution is clear, remains stable for several days, and can be used for cell culture stu