This paper presents a survey of recent approaches in the application o
f the object-oriented paradigm to formal specification, The complexity
of current information systems demands the use of a higher degree of
formalism in the development process, Formal languages such as Z, VDM
and Lotos have been used extensively in academic environments and rese
arch projects; however, their utilization in the 'real world' is still
relatively small, The use of object-oriented concepts has now been su
ggested as a good solution to the lack of expressiveness that characte
rizes most of these languages, Several approaches addressing this issu
e have appeared in the literature recently, including extensions to mo
st existing languages, In this paper we review some of these technique
s and discuss problems and issues relevant to the combination of forma
l methods and object orientation.