Abstract: A proximity alert system for monitoring the presence of at least one object, and has a portable master unit and at least one slave unit. The slave units are attachable to an object. the master unit has a warning member and a device for causing outputting of a warning signal when the distance between the master unit and at least one of the slave units exceeds a predetermined adjustable value. The master unit is adapted to control the connection to the slave units and cause a warning signal to output if a connection fails. An adhesive member is provided for attaching a slave unit to an object. The system is applicable to different kinds of objects, in particular, small objects and personal belongings like glasses, medicine contained in pill bottles, purses, keys, passports, credit cards, cameras, mobile phones, portable computers and PDAs.