Clinical Trials by Condition: O
- Obesity (11,155)
- Obesity Hypoventilation Syndrome (58)
- Obesity, Abdominal (261)
- Obesity, Maternal (58)
- Obesity, Metabolically Benign (19)
- Obesity, Morbid (853)
- Obsessive Behavior (2)
- Obsessive-Compulsive Disorder (519)
- Obstetric Labor Complications (2,797)
- Obstetric Labor, Premature (2,123)
- Occipital Horn Syndrome (2)
- Occupational Diseases (484)
- Occupational Injuries (13)
- Occupational Stress (287)
- Ochronosis (9)
- Ocular Cicatricial Pemphigoid (4)
- Ocular Hypertension (1,765)
- Ocular Hypotension (8)
- Ocular Melanoma (64)
- Ocular Motility Disorders (355)
- Ocular Muscular Dystrophy (7)
- Ocular Toxoplasmosis (4)
- Oculo-auriculo-vertebral Spectrum (10)
- Oculocerebral Syndrome With Hypopigmentation (5,216)
- Oculocerebrorenal Syndrome (6)
- Oculocutaneous Albinism (14)
- Oculomotor Nerve Diseases (4)
- Oculopharyngeal Muscular Dystrophy (12)
- Odontogenic Cysts (36)
- Odontogenic Tumors (7)
- Odontoma (1)
- Ogilvie Syndrome (3)
- Olfaction Disorders (87)
- Olfactory Nerve Diseases (19)
- Olfactory Nerve Injuries (2)
- Olfactory Neuroblastoma (66)
- Oligoastrocytoma (99)
- Oligodendroglioma (393)
- Oligohydramnios (28)
- Oligomenorrhea (11)
- Oligospermia (42)
- Oliguria (12)
- Olivopontocerebellar Atrophies (3)
- Ollier Disease (8)
- Omenn Syndrome (6)
- Onchocerciasis (30)
- Onchocerciasis, Ocular (8)
- Oncogenic Osteomalacia (14)
- Onycholysis (5)
- Onychomycosis (140)
- Open Bite (18)
- Ophthalmia Neonatorum (2)
- Ophthalmoplegia (139)
- Ophthalmoplegia, Chronic Progressive External (12)
- Opiate Overdose (63)
- Opioid-Induced Constipation (102)
- Opioid-Related Disorders (1,177)
- Opisthorchiasis (1)
- Opportunistic Infections (221)
- Opsoclonus-Myoclonus Syndrome (6)
- Optic Atrophies, Hereditary (46)
- Optic Atrophy (59)
- Optic Atrophy 1 (5)
- Optic Atrophy, Autosomal Dominant (5)
- Optic Atrophy, Hereditary, Leber (37)
- Optic Disk Drusen (4)
- Optic Nerve Diseases (412)
- Optic Nerve Glioma (19)
- Optic Nerve Hypoplasia (4)
- Optic Nerve Injuries (20)
- Optic Nerve Neoplasms (21)
- Optic Neuritis (170)
- Optic Neuropathy, Ischemic (48)
- Optic Pathway Glioma (44)
- Oral Cancer (564)
- Oral Hemorrhage (16)
- Oral Leukoplakia (34)
- Oral Manifestations (30)
- Oral Squamous Cell Carcinoma (200)
- Oral Submucous Fibrosis (10)
- Oral Ulcer (48)
- Orbital Cellulitis (3)
- Orbital Diseases (211)
- Orbital Fractures (17)
- Orbital Lymphoma (2)
- Orbital Neoplasms (11)
- Orbital Pseudotumor (4)
- Orchitis (5)
- Organic Acidemias (18)
- Organophosphate Poisoning (10)
- Ornithine Carbamoyltransferase Deficiency Disease (28)
- Ornithine Transcarbamylase Deficiency (30)
- Oroantral Fistula (3)
- Orofaciodigital Syndromes (3)
- Oropharyngeal Cancer, Adult (10)
- Oropharyngeal Neoplasms (299)
- Orotic Aciduria Type 1 (1)
- Orthomyxoviridae Infections (1,936)
- Orthostatic Intolerance (306)
- Ossification of Posterior Longitudinal Ligament (11)
- Ossification, Heterotopic (45)
- Osteitis (46)
- Osteitis Deformans (16)
- Osteoarthritis (4,953)
- Osteoarthritis, Hip (544)
- Osteoarthritis, Knee (2,829)
- Osteoarthritis, Spine (15)
- Osteoarthropathy, Primary Hypertrophic (2)
- Osteoarthropathy, Secondary Hypertrophic (1)
- Osteoblastoma (1)
- Osteochondritis (32)
- Osteochondritis Dissecans (27)
- Osteochondrodysplasias (238)
- Osteochondroma (28)
- Osteochondromatosis (13)
- Osteochondrosis (38)
- Osteofibrous Dysplasia (1)
- Osteogenesis Imperfecta (66)
- Osteogenesis Imperfecta Type I (1)
- Osteogenesis Imperfecta Type II (1)
- Osteogenesis Imperfecta Type III (11)
- Osteogenesis Imperfecta Type IV (2)
- Osteogenesis Imperfecta Type VI (6)
- Osteolysis (27)
- Osteolysis, Essential (3)
- Osteoma (11)
- Osteoma, Osteoid (9)
- Osteomalacia (48)
- Osteomyelitis (107)
- Osteonecrosis (162)
- Osteopetrosis (20)
- Osteopetrosis Autosomal Dominant Type 2 (1)
- Osteophyte (30)
- Osteoporosis (1,598)
- Osteoporosis, Postmenopausal (321)
- Osteoporosis-pseudoglioma Syndrome (2)
- Osteoporotic Fractures (98)
- Osteoradionecrosis (19)
- Osteosarcoma (633)
- Osteosarcoma, Juxtacortical (2)
- Osteosclerosis (27)
- Ostium Secundum Atrial Septal Defect (7)
- Otitis (349)
- Otitis Externa (27)
- Otitis Media (271)
- Otitis Media with Effusion (74)
- Otitis Media, Suppurative (14)
- Oto-Palatal-digital Syndrome (3)
- Oto-palato-digital Syndrome Type 1 (3)
- Otomycosis (10)
- Otorhinolaryngologic Diseases (5,999)
- Otorhinolaryngologic Neoplasms (1,194)
- Otosclerosis (17)
- Ototoxicity (50)
- Out-of-Hospital Cardiac Arrest (280)
- Ovarian Cancer (3,233)
- Ovarian Carcinosarcoma (32)
- Ovarian Cysts (774)
- Ovarian Diseases (3,172)
- Ovarian Epithelial Cancer (3,015)
- Ovarian Germ Cell Tumor (186)
- Ovarian Hyperstimulation Syndrome (76)
- Ovarian Low Malignant Potential Tumor (25)
- Ovarian Neoplasms (3,183)
- Ovarian Sex Cord Tumor With Annular Tubules (6)
- Ovarian Small Cell Carcinoma (4)
- Ovarian Torsion (11)
- Overbite (95)
- Overnutrition (4,596)
- Overweight (6,707)