A systematic comparison of the ginsenosides and anticancer activities was performed among white (air-dried) and red (steamed) roots of notoginseng (NG, Panax notoginseng), Asian ginseng (AG, P. ginseng), and American ginseng (AmG, P. quinquefolius). Chemical profiles of different ginseng species were characterized, through simultaneous quantification of nineteen major ginsenosides, by HPLC-UV at 202 nm. The antiproliferative and pro-apoptotic effects on human colorectal cancer cells were determined by MTS method and flow cytometry, respectively. Chemical analysis indicated that white NG possessed the most abundant ginsenosides, i.e., two- and five-fold higher than white AmG and AG. During the steaming process, extensive conversion of the original polar ginsenosides in white ginseng to new, less polar, degradation compounds in red ginseng was observed. White ginsengs produced weak antiproliferative effects, while red ginsengs exhibited a significant increase in antiproliferative and pro-apoptotic effects (both P < 0.01 vs. white ginseng). Among the three red ginsengs, red NG showed the best anticancer activity. Due to the low cost of NG and high bioactivity of red NG, the red NG is promising to be a useful botanical product in cancer chemoprevention.