Cloud condensation nuclei (CCN) measurements were made with the Desert Research Institute (DRI) instantaneous CCN spectrometer at the Korea Global Atmosphere Watch (GAW) Observatory (KGAWO) (36°32′N, 126°19′E) on the west coast of the Korean Peninsula from May 1–22, 2004. A TSI CPC3010 counter simultaneously measured condensation nuclei (CN). For seven of these days, submicron aerosol size distributions were also measured with an SMPS. Data were classified maritime or continental according to air mass back trajectories. Average maritime and continental CCN concentrations at 1% supersaturation were 2406 cm⁻³ and 5292 cm⁻³, respectively, while CN concentrations were 3983 cm⁻³ and 8313 cm⁻³, respectively. The average ratios of CCN to CN concentrations were 0.64 for both maritime and continental. These results suggest ubiquitously high aerosol concentrations in this area regardless of air mass origin.