Three samples of a dry com. compost made of sewage sludge, straw and org. wastes were extd. with hexane-Me2CO mixt. in Soxhlet app. or in presence of ultrasounds to recover poly chlorinated biphenyls (PCBs). They were isolated M from the exts. by adsorption on SiO2 get and analyzed by gas chromatog. The content of PCBs was 28 to 400 mu g/kg. it Use of the ultrasonic extn. resulted in decreasing the scatter of results of PCB detn. The detd. PCB content was lower than the std. allowable one (800 mu g/kg).