In earlier studies non-Hodgkin's lymphoma (NHL) has been associated with exposure to phenoxyacetic acids or chlorophenols, but also impurities such as polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are of concern since these compounds as well as polychlorinated biphenyls (PCBs) are immunotoxic and promoters in carcinogenesis. The aim of this study was to determine the concentrations of specific PCDDs, PCDFs and PCBs, 1,1-dichloro-2, 2-bis(p-chlorophenyl) ethylene (p,p'-DDE), and hexachlorobenzene (HCB) in cases with NHL and surgical controls: The study included 28 NHL cases of the B-cell type and 17 controls. Seven PCDDs and 10 PCDFs substituted with chlorine in the 2,3,7,8-position and three co-planar PCB congeners were determined in 20 cases and 17 controls without showing differences. Almost all of the analysed PCB congeners were higher, PCB No. 156, No. 157, sum of No. 182 and 187, No. 171, sum of No. 172 and No. 192, sum of No. 170 and No. 190, No. 189, No. 202, No. 201, No. 194, and No. 208 significantly so (p<0.05), in 27 NHL cases compared with the 17 controls. The mean sum of PCBs was for the cases 1614 ng/g lipid, range 637-4705, versus 1213 for the controls, range 366-2282 (p=0.06). An odds ratio of 2.7, 95% confidence interval 0.8-9.4, was obtained for cases with the sum of PCBs higher than the median concentration of 1300 ng/g lipid. The sum of PCBs was similar for different stages of NHL. No significant differences were found between the 28 cases and 17 controls regarding p,p'-DDE and HCB.