Lately, interest has focussed on the environmental presence of phenolic organochlorines with endocrine disrupting potential, including pentachlorophenol (PCP) and phenolic PCB-metabolites, and human exposure to these compounds. The present study,aims at determining ten congeners of polychlorinated biphenyls (PCB), three major hydroxylated PCB metabolites (4OH-CB107, 4OH-CB146, 4OH-CB187), and pentachlorophenol (PCP) in serum from 30 pregnant and breast-feeding women from Uppsala County, Sweden. The studied PCB congeners included both dioxin-like mono-ortho PCBs (CB105, CB118, CB156 and CB167) and di-ortho PCBs with no reported dioxin-like activity (CB138, CB153, and CB180). Results showed that the median levels of ΣPCB decreased from 226 ng/g serum lipid in early pregnancy to 150 ng/g serum lipid in late pregnancy. This pattern of decreasing PCB levels during pregnancy was also evident when looking at the single PCB congeners. The clear decrease in levels of these substances during pregnancy show that it is important to sample blood from pregnant women within a short period of time during pregnancy in order to avoid variation in PCB levels due to sampling timing within a study. Moreover, it is important to know the timing of sample collection when comparing different studies reporting serum/plasma concentrations of PCB in pregnant women. Among the three hydroxylated PCB metabolites analysed in this study, concentrations did not vary significantly during pregnancy. 4OH-CB187 showed highest levels in serum of the three with median concentration of 0.2 ng/g serum. Metabolites 4OH-CB146 and 4OH-CB187 were correlated to its parent compounds whilst 4OH-CB107 was not. This might indicate another source of exposure of 4OH-CB107, which is unknown today. The metabolite 4OH-CB107 significantly increased in serum from late pregnancy (week 31-36) to three weeks after delivery, whereas the levels of the other two metabolites did not change significantly during this time. PCP showed the highest median serum concentrations of the compounds analysed on wet weigh basis, up to 3 ng/g serum in early pregnancy. Serum levels of PCP did not change significantly during pregnancy and showed no correlation between early and late pregnancy. However, a significant increase was observed from late pregnancy to three weeks after delivery. This study shows that PCB and several phenol compounds, of which PCP is dominating, are found in the blood of pregnant and lactating Swedish women, and that the levels in some cases may change during the studied period If the levels of the analysed compounds in pregnant women may pose a health risk to the fetus has still to be determined.