Parenchymal cells were obtained from adult rats by a collagenase perfusion technique and cultured as monolayers in serum-free media. Amino acid transport was assayed by measuring the uptake of non-metabolizable amino acid, AIB. AIB transport system was depressed in liver cells cultured from rats treated with 10 ug/Kg, and 25 ug/Kg TCDD. Ouabain transport system was also depressed by 5 ug/Kg, 10 ug/Kg, and 25 ug/Kg TCDD and more severely damaged than AIB uptake. But, TAT activity induction was depressed by only 25 ug/Kg TCDD. The toxic effect of TCDD was more developed as the time elapsed.