Hairy roots of Korean ballon flower (Platycodon grandiflorum A. DC) were induced from the root tissues infected with Agrobacterium rhizogenes ATCC 15834. Growth and polyacetylene [lobetyol (1), lobetyolin (2) and lobetyolinin (3)] production fo ten hairy root clones cultured in 1/4 Gamborg B5 (B5) liquid medium were determined. One selected hairy root clone (D6) grew well in hormone free-B5 liquid medium and showed maximum content of polyacetylenes at week 6 for 1 (0.375% dry wt) and at week 7 for 2 and 3 (3.030% and 0.206% dry wt, respectively) whose levels were much higher than those of the intact plant root (1:0.019%, 2:0.077% dry wt, 3 was not detected).