The immigration of foreign workers has important public health implications because it is a potential route for disease transmission. New diseases may be introduced into the country and diseases which have been eradicated may re-emerge among the local population. The emergence of new diseases and re-emergence of previously eradicated diseases will have grave public health implications because the local population has no or decreased immunity against these diseases. The mobility of foreign workers withing the country sometimes makes it difficult for the health authorities to track the source of infection. Foreign workers who are carriers of diseases such as Hepatitis B and HIV (which have a window period) will test as negative and hence will not be detected during the pre-employment medical examination. Thus it is essential that these foreign workers undergo a full medical examination and screening withing 3 to 6 months after entry into Malaysia and annually throughout their employment period in Malaysia. The current physical examination and screening procedure does not guarantee that these workers are totally disease-free. Therefore, we need to re-look at the current examination content, criteria and procedures to rectify any deficiencies in the current system. The authorities need to devise a mechanism to ensure that foreign workers or their employers purchase a medical insurance so that the public sector health facilities and personnel are not overloaded and overworked. The authorities have already in place a mechanism to prevent medically UNFIT foreign workers from entering this country. However, it is the large number of undocumented and illegal foreign workers that pose a bigger threat to the wellbeing of the nation's health. As long as employers are willing to take a risk by employing illegal foreign workers, all the efforts that the government has undertaken to safeguard the nation's health will be rendered futile.