| AAAI | American Association ForArtificial Intelligence | - | Medical |
| AAAS | American Association For The Advancement Of Science | - | Medical |
| AACC | American Association For Clinical Chemistry | - | Medical |
| AACR | American Association For Cancer Research | - | Medical |
| AAI | American Association Of Immunologists | - | Medical |
| AAIP | American Association Of Investigative Pathologists | - | Medical |
| AANP | American Association Of Neuropathologists | - | Medical |
| AAP | Association Of American Physicians | - | Medical |
| ABA | Australian Biotechnol. Assoc. | - | Medical |
| ABI | Applied Biosystems | - | Medical |
| ABIC | Agricultural Biotechnology Intl. Conf. | - | Medical |
| ABRF | Association Of Biomolecular Resource Facilities | - | Medical |
| ACE | Angiotensin-converting Enzyme | - | Medical |
| ACEDB | A C. Elegans Database | - | Medical |
| ACMG | American College Of Medical Genet. | - | Medical |
| ACS | American Chemical Society | - | Medical |
| ADA | Americans With Disabilities Act | - | Medical |
| AEC | Atomic Energy Commission | - | Medical |
| AES | American Electrophoresis Society | - | Medical |
| AFIP/ARP | Armed Forces Inst. Of Pathol./Am. Registry Of Pathol. | - | Medical |
| AFMR | American Federation Of Medical Research | - | Medical |
| AGSG | Alliance Of Genetic Support Groups (now Genetic Alliance) | - | Medical |
| AGT | Association Of Genetic Technologists | - | Medical |
| AHA | American Heart Association | - | Medical |
| AIBS | Am. Inst. Of Biol. Soc. | - | Medical |
| AIDS | Acquired Immune Deficiency Syndrome | - | Medical |
| AMIA | American Medical Informatics Association | - | Medical |
| ANGIS | Australian National Genomic Info. Service | - | Medical |
| ANL | Argonne National Laboratory | - | Medical |
| API | Application Programming Interface | - | Medical |
| ARP | American Registry Of Pathology | - | Medical |
| ASB | American Society For Biotechnology | - | Medical |
| ASBMB | American Society For Biochemistry & Molecular Biology | - | Medical |
| ASCB | American Society For Cell Biology | - | Medical |
| ASCI | American Society For Clinical Investigation | - | Medical |
| ASHG | American Society For Human Genetics | - | Medical |
| ASIP | American Society For Investigative Pathologists | - | Medical |
| ASIS | American Society For Information Science | - | Medical |
| ASLME | American Society Of Law | - | Medical |
| ASM | American Society For Microbiology | - | Medical |
| ASPET | American Society For Pharmacology And Experimental Therapeutics | - | Medical |
| ATCC | American Type Culture Collection | - | Medical |
| ATP | Advanced Technology Program | - | Medical |
| AVS | American Vacuum Society | - | Medical |
| AWCH | Adelaide Women And Children's Hospital | - | Medical |
