Diagnosaurus
- Tachycardia, multifocal atrial
- Tachycardia, paroxysmal supraventricular
- Tachycardia, sinus
- Tachycardia, ventricular
- Taenia (tapeworms)
- Takayasu's arteritis
- Tall stature
- Tamponade, cardiac
- Tapeworms
- Temporal (giant cell) arteritis
- Tenosynovitis, volar flexor
- Testicular cancer
- Testicular torsion
- Tetanus
- Thalassemia
- Thoracic aortic aneurysm
- Thoracic outlet syndrome
- Thromboangiitis obliterans
- Thrombocytosis
- Thrombophlebitis, superficial
- Thrombosis
- Thrombosis, deep-vein
- Thrombotic thrombocytopenic purpura
- Thrush
- Thyroid cancer
- Thyroid enlargement (goiter)
- Thyroid hormone deficiency
- Thyroid hormone excess
- Thyroiditis
- Thyrotoxicosis
- TIA
- Tinea corporis
- Tinea cruris (jock itch)
- Tinea manuum
- Tinea pedis
- Tinea unguium
- Tinea versicolor
- Tinnitus
- Tongue, red & smooth (glossitis)
- Tonsillitis
- Tophaceous gout
- Tourette's syndrome
- Toxic shock syndrome
- Toxidromes
- Toxoplasmosis
- Tracheal obstruction
- Transient ischemic attack
- Traveler's diarrhea
- Tremor
- Trichinosis (Trichinella infection)
- Trichuriasis (whipworm)
- Tricuspid regurgitation
- Tricuspid stenosis
- Tricyclic antidepressant overdose
- Trigeminal neuralgia
- Triglycerides increased
- Trypanosomiasis, African
- Trypanosomiasis, American
- TTP
- Tuberculosis
- Tuberculosis of bone & joints
- Tubular necrosis, acute
- Tularemia
- Tumor, bone
- Tumor, brain
- Tumor, colorectal
- Tumor, esophageal
- Tumor, gastric
- Tumor, laryngeal
- Tumor, liver
- Tumor, lung
- Tumor, ovarian
- Tumor, renal
- Tumor, salivary gland
- Tumor, small intestine
- Tumor, thyroid
- Tumors, cardiac
- Tumors, nasal
- Turner syndrome
- Tylenol poisoning
- Typhoid fever