It is well known that polycyclic aromatic hydrocarbons (PAHs) are absorbed through the skin of experimental animals and humans. However dermal uptake of PAHs is difficult to assess due to the lack of specific studies. The aim of this study was to obtain in vitro percutaneous absorption data for phenanthrene. In vitro penetration was measured with excised monkey (Cercopithecus Aethiops) skin in Franz diffusion cells, using a saline solution with 4% bovine serum albumin and gentamicin sulfate as receptor fluid. In two different groups of 7 and 2 cells, 38.1 and 95.3 nmol/cm2 respectively of phenanthrene were applied in an acetone vehicle. The absorption rate in the first group of 7 cells was 0.025 nmol/cm2/h (S.D. = 0.012), the lag time 11.7 (S.D. = 7.0) h and the breakthrough time 70 m (S.D. = 55 m). In the second group of 2 cells, the average absorption rate was 0.066 nmol/cm2/h and the average lag time 11.8 h. The percutaneous absorption at 24, 48 and 72 hours in the 7 cell group was 0.72% (S.D. = 0.52), 2.51% (S.D. = 1.76) and 3.9% (S.D. = 2.0) of the applied dose respectively. In the 2-cell group 1.1%, 2.78% and 4.5% of the applied dose was absorbed at 24, 48 and 72 hours. The results of the present study confirm the extent of percutaneous absorption of phenanthrene. The data can be compared with dermal absorption values of other PAHs obtained under the same experimental conditions.