We synthesized single-wall carbon nanotubes (SWNTs), 1.2-1.4 nm in diameter, and aggregates of single-wall carbon nanohoms (SWNHs) by CO2 laser vaporization in Ar gas under pressures of 150-760 Torr. At 150 Torr, SWNTs with smaller diameters were synthesized together with amorphous carbon. With an increase in the gas pressure, the yield of SWNTs decreased, the tube diameters increased, and SWNH aggregates were synthesized. At 760 Torr, most of the products were SWNH aggregates. We discuss the temperature-dependent growth of the SWNTs and SWNH aggregates originating in supersaturated carbonaceous vapors confined by Ar gas. (C) 2002 Published by Elsevier Science B.V.