Human liver slices were prepared with a Krumdieck slicer from macroscopically healthy surgical waste after partial hepatectomy. They were incubated without or with the addition of the inducer beta-naphthoflavone (BNF) (25 mum) either immediately after preparation (fresh slices) for up to 24 hours or after cryopreservation in liquid nitrogen (thawed slices) for up to 6 hours. Potassium concentration was well maintained in fresh and thawed slices over 24 and 6 hours, respectively, but at lower levels than in rat liver slices. Albumin secretion showed relatively large interindividual differences. Both parameters were lower in thawed slices than in fresh ones, but indicated a certain number of viable cells. In untreated fresh slices CYP1A1-mRNA was not detectable; however, it increased distinctly within 6 hours of exposure to BNF. The amounts of induced CYP1A1-mRNA differed by a factor of more than 100 among six human livers and were lower than in fresh rat liver slices. Even in thawed human slices, CYP1A1-mRNA expression could be induced in vitro by BNF, although at a very low level and preferentially in those specimens with comparably high inducibility already before freezing.