We have described the SMC-PTS and reviewed the current status of the project overall. Two rotating gantry rooms with a multi-purpose nozzle and a dedicated pencil beam scanning nozzle will be used for the proton beam therapy of cancer patients at SMC-PTS. It will be capable of treating over than 480 new patients per year under 8-hour daily operation.A clinical commissioning following the machine commissioning will be intensively conducted with mock-up treatments for each clinical case thoroughly and it will guarantee a precise and accurate proton beam treatment at SMC-PTS.Along with the clinical commissioning, we will measure relative biological effectiveness (RBE) values with various conditions for proton beam at SMC. Although a universal RBE of 1.1 has been widely used in clinical proton beam therapy [6], a recent study indicated that a fixed RBE is not ideal for proton treatment planning [7]. The RBE varies with different parameters such as linear energy transfer, dose per fraction, and tissue type. With the RBE measurement at SMC-PTS, further study of RBE-based proton treatment planning can be carried on.With all the machine and clinical commissioning, we are working toward a successful launching of the first private-hospital based proton therapy center in Korea on schedule to be operational in 2015.