This paper introduces a new class of codes that have been called ‘unequal error locating codes’. These codes are basically error locating codes but are studied by considering error patterns of various magnitudes lying in different sub-blocks of unequal lengths of the block length of a code. Lower and upper bounds on the number of parity-check digits required for such codes are derived. First, the codes locating random errors are considered and then a similar study is carried out for codes locating burst errors. Both cases are illustrated.