Complementary and alternative medicine use is increasing worldwide. Expenses for complementary and alternative medicines are high, while the effectiveness of such medicines is still in debate. This paper reviewed the utilization of complementary and alternative medicines. Complementary and alternative therapies are used frequently and increasingly. Alternative therapies were used often for chronic conditions, including back problems, anxiety, depression and headaches in the United States. Musculoskeletal and respiratory complaints were the most frequent causes for complementary and alternative medicine consultation in Israel. In Taiwan, a systematic series of studies on factors related to utilization of traditional Chinese medicine (TCM) were conducted, including: (1) factors related to the choice of medical service (single or dual approach); (2) factors related to the choice of clinic type between TCM and western medicine among patients with single approach and among patients with dual approach; (3) factors related to patient choice of institute providing TCM (between TCM department in teaching hospital and regular TCM clinic) among patients using TCM only; and (4) knowledge, attitude and behavioral intention regarding TCM among patients using TCM only and among community residents over 30 years old. The findings of the above studies are summarized and presented accordingly.