Total particle number concentrations and particle size distributions in the diameter range 3--800 nm were measured in continental Antarctica during the austral summers 2000 and 2001. Observed total particle number concentrations varied between about 200 and 2000 cm-3, with on average higher concentrations in marine/coastal air masses than in continental air masses. Concentrations in excess of about 300--400 cm-3 were attributable to the presence of small (<20 nm) nucleation mode particles. Measured size distributions were fitted with two to four lognormal modes. All the spectra displayed an accumulation mode peaking at about 70--150 nm and an Aitken mode peaking at about 30--50 nm. The average mean diameter of the accumulation mode was much lower in continental air masses, whereas that of the Aitken mode was almost the same for the two air mass types. A nucleation mode was present in more than a half of the measured spectra, and occasionally two nucleation modes could be identified. Evidence on recent new particle formation with subsequent particle growth up to about 40 nm was observed in marine/coastal air masses only. Our measurements indicate that these recently formed particles contribute significantly to the overall particle budget of the Antarctic boundary layer, and they can be also a source of climatically important Aitken and accumulation mode particles.