Clinical Trials by Condition: O
- Obesity (8,956)
- Obesity Hypoventilation Syndrome (47)
- Obesity, Abdominal (197)
- Obesity, Metabolically Benign (12)
- Obesity, Morbid (671)
- Obsessive Behavior (2)
- Obsessive-Compulsive Disorder (421)
- Obstetric Labor Complications (2,186)
- Obstetric Labor, Premature (1,659)
- Occipital Horn Syndrome (1)
- Occupational Diseases (300)
- Occupational Injuries (9)
- Occupational Stress (149)
- Ochronosis (8)
- Ocular Cicatricial Pemphigoid (4)
- Ocular Hypertension (1,481)
- Ocular Hypotension (7)
- Ocular Melanoma (52)
- Ocular Motility Disorders (278)
- Ocular Muscular Dystrophy (3)
- Ocular Toxoplasmosis (4)
- Oculocerebral Syndrome With Hypopigmentation (4,039)
- Oculocerebrorenal Syndrome (5)
- Oculocutaneous Albinism (14)
- Oculomotor Nerve Diseases (4)
- Oculopharyngeal Muscular Dystrophy (12)
- Odontogenic Tumors (4)
- Ogilvie Syndrome (1)
- Olfaction Disorders (37)
- Olfactory Nerve Diseases (17)
- Olfactory Nerve Injuries (2)
- Olfactory Neuroblastoma (64)
- Oligoastrocytoma (93)
- Oligodendroglioma (367)
- Oligohydramnios (20)
- Oligomenorrhea (9)
- Oligospermia (30)
- Oliguria (11)
- Olivopontocerebellar Atrophies (2)
- Ollier Disease (7)
- Omenn Syndrome (6)
- Onchocerciasis (24)
- Onchocerciasis, Ocular (6)
- Oncogenic Osteomalacia (11)
- Onycholysis (5)
- Onychomycosis (119)
- Open Bite (9)
- Ophthalmia Neonatorum (2)
- Ophthalmoplegia (105)
- Ophthalmoplegia, Chronic Progressive External (7)
- Opioid-Related Disorders (636)
- Opportunistic Infections (209)
- Opsoclonus-Myoclonus Syndrome (6)
- Optic Atrophies, Hereditary (37)
- Optic Atrophy (43)
- Optic Atrophy 1 (5)
- Optic Atrophy, Autosomal Dominant (5)
- Optic Atrophy, Hereditary, Leber (31)
- Optic Disk Drusen (2)
- Optic Nerve Diseases (316)
- Optic Nerve Glioma (17)
- Optic Nerve Injuries (15)
- Optic Nerve Neoplasms (18)
- Optic Neuritis (122)
- Optic Neuropathy, Ischemic (44)
- Optic Pathway Glioma (43)
- Oral Cancer (450)
- Oral Hemorrhage (14)
- Oral Leukoplakia (28)
- Oral Manifestations (20)
- Oral Squamous Cell Carcinoma (46)
- Oral Submucous Fibrosis (9)
- Oral Ulcer (32)
- Orbital Cellulitis (3)
- Orbital Diseases (152)
- Orbital Fractures (14)
- Orbital Lymphoma (2)
- Orbital Neoplasms (7)
- Orbital Pseudotumor (4)
- Orchitis (3)
- Organic Acidemias (9)
- Organophosphate Poisoning (10)
- Ornithine Carbamoyltransferase Deficiency Disease (19)
- Ornithine Transcarbamylase Deficiency (19)
- Orofaciodigital Syndromes (2)
- Oropharyngeal Cancer, Adult (9)
- Oropharyngeal Neoplasms (233)
- Orotic Aciduria Type 1 (1)
- Orthomyxoviridae Infections (1,709)
- Orthostatic Intolerance (225)
- Ossification of Posterior Longitudinal Ligament (5)
- Ossification, Heterotopic (29)
- Osteitis (33)
- Osteitis Deformans (15)
- Osteoarthritis (3,904)
- Osteoarthritis, Hip (415)
- Osteoarthritis, Knee (2,115)
- Osteoarthritis, Spine (11)
- Osteoarthropathy, Primary Hypertrophic (2)
- Osteoarthropathy, Secondary Hypertrophic (1)
- Osteoblastoma (1)
- Osteochondritis (29)
- Osteochondritis Dissecans (25)
- Osteochondrodysplasias (188)
- Osteochondroma (19)
- Osteochondromatosis (13)
- Osteochondrosis (26)
- Osteofibrous Dysplasia (1)
- Osteogenesis Imperfecta (52)
- Osteogenesis Imperfecta Type II (1)
- Osteogenesis Imperfecta Type III (8)
- Osteogenesis Imperfecta Type IV (1)
- Osteogenesis Imperfecta Type VI (3)
- Osteolysis (23)
- Osteolysis, Essential (3)
- Osteoma (6)
- Osteoma, Osteoid (6)
- Osteomalacia (39)
- Osteomyelitis (82)
- Osteonecrosis (138)
- Osteopetrosis (21)
- Osteopetrosis Autosomal Dominant Type 2 (1)
- Osteophyte (21)
- Osteoporosis (1,378)
- Osteoporosis, Postmenopausal (263)
- Osteoporosis-pseudoglioma Syndrome (2)
- Osteoporotic Fractures (72)
- Osteoradionecrosis (14)
- Osteosarcoma (520)
- Osteosarcoma, Juxtacortical (1)
- Osteosclerosis (25)
- Ostium Secundum Atrial Septal Defect (6)
- Otitis (303)
- Otitis Externa (24)
- Otitis Media (239)
- Otitis Media with Effusion (65)
- Otitis Media, Suppurative (8)
- Oto-Palatal-digital Syndrome (2)
- Oto-palato-digital Syndrome Type 1 (2)
- Otomycosis (7)
- Otorhinolaryngologic Diseases (4,596)
- Otorhinolaryngologic Neoplasms (908)
- Otosclerosis (12)
- Out-of-Hospital Cardiac Arrest (210)
- Ovarian Cancer (2,627)
- Ovarian Carcinosarcoma (27)
- Ovarian Cysts (620)
- Ovarian Diseases (2,539)
- Ovarian Epithelial Cancer (2,463)
- Ovarian Germ Cell Tumor (184)
- Ovarian Hyperstimulation Syndrome (69)
- Ovarian Low Malignant Potential Tumor (25)
- Ovarian Neoplasms (2,578)
- Ovarian Sex Cord Tumor With Annular Tubules (5)
- Ovarian Small Cell Carcinoma (2)
- Overbite (52)
- Overnutrition (3,537)
- Overweight (5,253)