| Abattoirs to Acanthopanax |
| Acanthopodina to Acetylglucosamine |
| Acetylglucosaminidase to Acrodynia |
| Acromegaly to Acute Disease |
| Acute Toxicity Tests to Adenomyoma |
| Adenophorea to Adolescent |
| Adolescent Behavior to Aerospace Medicine |
| Aesculus to AIDS Dementia Complex |
| AIDS Serodiagnosis to Aldehyde Oxidase |
| Aldehyde Oxidoreductases to Allylglycine |
| Allylisopropylacetamide to Aluminum Silicates |
| Alveolar Bone Loss to Amino Acid Chloromethyl Ketones |
| Amino Acid Isomerases to Ammotherapy |
| Amnesia to Anal Gland Neoplasms |
| Anal Sacs to Anemia, Macrocytic |
| Anemia, Megaloblastic to Angioscopy |
| Angiosperms to Anniversaries and Special Events |
| Annona to Anti-HIV Agents |
| Anti-Infective Agents to Antigens, Archaeal |
| Antigens, Bacterial to Antigens, Thy-1 |
| Antigens, Tumor-Associated, Carbohydrate to Aorta |
| Aorta, Abdominal to Appendix |
| Appetite to Arcidae |
| Arcobacter to Artemisia |
| Artemisia absinthium to Asbestos, Crocidolite |
| Asbestos, Serpentine to Association |
| Association Learning to Attention Deficit Disorder with Hyperactivity |
| Attitude to Avian Proteins |
| Aviation to Azygos Vein |