The membership of the IUBS presently consists of 44 National Members, adhering through Academies of Sciences, National Research Councils, national science associations or similar organisations, as well as 80 Scientific Members, all of which are international scientific associations, societies or commissions in the various biological disciplines.
The Union comprises:
National or Ordinary Members representing countries or other territories,
Scientific Members concerned with a particular discipline in the biological sciences, and Associate Members aspiring to Ordinary Membership.
An Ordinary Member may be any country, territory or geographic region in which the study of the biological sciences has developed independently. The adhering organization may be its principal Scientific Academy, its Research Council or any other appropriate institution.
A Scientific Member may be any international society, association or body that represents a biological discipline, or a discipline relevant to the scientific study of biology.
An Associate Member may be any country, territory or geographic region in which the infrastructure of biological sciences has not reached the levels of development of most Ordinary Members. The Executive Committee will decide on a case by case basis about appropriate ways to involve that Associate Member in IUBS and to assist its development into full Ordinary Membership. The status of Associate Members should be reviewed every three years.