Tachycardia
Takayasu's arteritis
Tapeworm infection
Temporal lobe seizure
Tendinitis
Tennis elbow
Tension headache
Testicular cancer
Testicular torsion
Tetanus
Tetralogy of Fallot
Thalassemia
Thoracic aortic aneurysm
Thoracic outlet syndrome
Throat cancer
Thrombocytopenia (low platelet count)
Thrombocytosis
Thrombophlebitis
Thumb arthritis
Thunderclap headaches
Thyroid cancer
Thyroid nodules
Tinea versicolor
TMJ disorders
Toe walking in children
Tongue tie (ankyloglossia)
Tonsillitis
Tooth abscess
Torn meniscus
Tourette syndrome
Toxic hepatitis
Toxic shock syndrome
Toxoplasmosis
Trachoma
Transient global amnesia
Transient ischemic attack (TIA)
Transposition of the great arteries
Transverse myelitis
Traumatic brain injury
Traveler's diarrhea
Trench mouth
Trichinosis
Trichomoniasis
Tricuspid atresia
Trigeminal neuralgia
Trigger finger
Triple X syndrome
Truncus arteriosus
Tuberculosis
Tuberous sclerosis
Turner syndrome
Typhoid fever
Typhoidal tularemia