Misr Chemical Industries [MCI] is located in El-Mex industrial area, to the west of Alexandria City. Chloralkali production in MCI started in 1960 using mercury-amalgam electrolysis and continued operation of the facility for over 35 years, far beyond the design service life of 20 years, has caused increased emissions and frequent leaks to air and water from the processing equipment, which posed serious occupational hazards to the exposed workers and severe environmental problems in the vicinity of MCI. A hazardous waste landfill [HWL] has been established on 1998 for containing derbies of MCI to reduce environmental and health risks to reasonable levels. The site of the HWL is approximately 80 km southwest of El-Mex area where MCI facilities are located, at Alam El-Afrag on edge of the western desert. The study aimed at monitoring the HWL site for possible leakage of mercury vapour to air. Measurements were made by using the mercury vapour analyzer. The study began after five years from the final closure of the landfill on 2002 and extended for three years till the end of 2004. It was found that the HWL site selection complies with law 4/1994, Article 28. The mercury vapour readings in the site were almost not detected which assured the good performance of the mercury decontamination project of Misr Chemical Industries.