The inhibition of phenylpropanoid biosynthesis by 2-aminoindan-2-phosphonic acid (AIP) in alfalfa suspension cultures (Medicago sativa L.) was associated with a marked decline in the content of cinnamic acid derivatives during the whole subculture interval. The levels of all investigated forms of phenolic acids in AIP-treated cells were lower than those of control with the exception of free phenolic acids on days<space>1 and 2. The dynamics of free IAA content in AIP-treated cells was similar to that of the control but its peak was significantly lower. The auxin content in AIP-treated cells on days<space>9 and 11 represented only 35 and 40<space>% of control values, respectively. AIP-treatment stimulated soluble peroxidase (EC 1.11.1.7) activity in the first 2<space>d after cell inoculation. Time-course of soluble IAA-oxidase activities was similar to that of soluble peroxidases (with the exception of the drop in peroxidase activity on day<space>3) but beginning day<space>6, the enzyme activities in AIP-treated cells were significantly lower until the end of the subculture interval.