| R-CHP | Rituximab+Cyclophosphamide+Doxorubicin+Prednisone |
| RA | Receptor Antagonist |
| RA | Refractory Anemia |
| RA Rheuma. | Rheumatoid Arthritis |
| RAA | recurrent Amino Acid |
| RACP | Radiation Activated Cytotoxin Prodrug (oncology) |
| RAEB | Refractory Anemia with Excess Blasts |
| RAFT | Reversible Addition Fragmentation chain Transfer |
| RAGE | Receptor for Advanced Glycation End products |
| RAGE | Random Activation of Gene Expression |
| RAM | Ram Access Memory |
| RANK | Receptor Activator of Nuclear factor Kappa B |
| RANKL | Receptor Activator of Nuclear factor Kappa B Ligand |
| RAP | Receptor-Associated Protein |
| RAPD | Random Amplified Polymorphic DNA |
| RAPID | Regulated Accumulation of Protein for Immediate Delivery (Therapeutic protein delivery technique) |
| RAR | Retinoic Acid Receptor |
| RARS | Refractory Anemia with Ringed Sideroblasts |
| RAS | Renin-Angiotensin System |
| RASP | Real-time web APP. Security & Protection |
| RB | Retino Blastoma |
| RBC | Red Blood Cell |
| RBLI | Recovery Boiler Leak Indication |
| RBS | Retained Blood Syndrome |
| RC | Re Combinant |
| RC | Resistance Capacitance |
| RCC | Reinforced Carbon-Carbon |
| RCC | Red Cell Concentrates |
| RCC Onco. | Renal Cell Carcinoma |
| RCL | Rotator Cuff Lesion |
| RCM | Ring Closing Metathesis |
| RCP | Riboflavin Carrier Protein |
| RCS | Resin Coated Sand |
| RCT | Reverse Cholesterol Transport (See RLT) |
| RD | Respiratory Depression |
| RDA | Required Dosage Amount |
| RDAF | Recombinant Direct Acting Fibrinolytic |
| RDEB | Recessive Dystrophic Epidermolysis Bullosa |
| RDN | Renal De Nervation |
| RDS | Respiratory Distress Syndrome |
| RE | RE Issue (USA Patents) |
| REACH | Registration, Evaluation, Authorization &, CHemical Substances |
| REMS | Risk Evaluation and Mitigation Strategy |
| REOS | Rapid Elimination Of Swill (pharma drug discovery/screening method) |
| REOVirus | Respiratory Enteric Orphan Virus |
| RESIST. | Resistance |
| RET | REarranged during Transfection (Oncology) |
| RF | Radio Frequency |
| RFA | Radio Frequency Ablation |
| RFB | Redox Flow Battery |
| RFD | Refuse Fuel Derived |
| RFID | Radio Frequency IDentification |
| RFP | Request For Proposals |
| RFQMR | Rotational Field Quantum Magnetic Resonance |
| RGE | Rotavirus Gastro Enteritis |
| RH | Radio Hybrid |
| RH Pneumo. | Respiratory Health |
| Rha | Rhamnose |
| rHA | Recombinant Hem Agglutinin |
| rHDL | Reconstituted High Density Lipoprotein |
| rhGAA | recombinant human GAA |
| rhIGF | Recombinant Human Insulin-like Growth Factor |
| rhSOD | Recombinant Human Super Oxide Dismutase |
| RIE | Reactive Ion Etch |
| RIE | Right sided Infective Endocarditis |
| RIGS | Radio Immuno Guided Surgery |
| RIM | Reaction Injection Molding |
| RIME | Receptor-Induced Magnetic Enhancement |
| RIPA | Ristocetin Induced Platelet Aggregation |
| RISC | RNA Induced Silencing Complex (RNAI) |
| RLD | Reference Listed Drug |
| RLS | Restless Legs Syndrome |
| RLT | Reverse Lipid Transport |
| RMB | Rapid Melt Beads (Pharma.>Drug Delivery) |
| RMD | Respiratory Monitoring Device |
| RMM | Remote Monitoring and Management |
| RMS | Relapsing MS |
| RNAI | RNA Interference |
| RNP | Ribo Nucleo Protein |
| RO | Reverse Osmosis |
| ROA | Raman Optical Activity |
| ROCK | RhO associated Coiled-coil Kinase |
| ROM | Read Only Memory |
| ROMP | Ring - Opening Metathesis Polymerization |
| ROP | Ring Opening Polymn. |
| ROP | Retinopathy Of Prematurity |
| ROP | Recombinant Overlapping Peptide |
| ROS | Reactive Oxygen Species |
| RP | Retinitis Pigmentosa |
| RP-HPLC | Reversed Phase capillary HPLC (Abbrev.) |
| rPA | Recombinant Protective Antigen (anthrax vaccine) |
| RPD | Rapid Plasma Deposition |
| RPE | Retinal Pigment Epithelium |
| RPE | Referential Preservation Engine (Web-Sites) |
| rPFS | radiographic Progression-Free Survival |
| RPM | Remote Patient Monitoring |
| RPPA | Reverse Phase Protein Array |
| RRAM | Resistive Random Access Memory |
| RRMM | Relapsed or Refractory MM |
| RRMS | Relapsing-Remitting Multiple Sclerosis |
| RS | Serbia |
| RS | ring sideroblasts |
| RSA | Reverse Shoulder Arthroplasty |
| RSD | Reflex Sympathetic Dystrophy |
| RSS | "Really Simple Syndication" or "Rich Site Summary" |
| RSV | Respiratory Syncytial Virus |
| RT | Retention Time |
| RT Onco. | Radio Therapy |
| RTA | Ready To Administer |
| RTC | Rear Toe Control |
| RTF | Real Time Focusing |
| RTH | Resistance to Thyroid Hormone |
| RTI | Reverse Transcriptase Inhibitor |
| RTI | Respiratory Tract Infections |
| RTM | Resin Transfer Molding |
| RTM | Registered Trade Mark |
| RTM | Real Time Monitoring |
| RTOR | Real Time Oncology Review |
| rtPA | Recombinant Tissue Plasminogen Activator (thrombolytic agent) |
| RTS | Radiation Therapy System |
| RTV | Room Temperature Vulcanizable |
| RTV Lung | Relative Tidal Volume |
| RU | RUssia |
| RUO | Research Use Only |
| RV | Recreational Vehicles |
| RVI | Right Ventricular Involvement |
| RVO | Retinal Vein Occlusion |
| RVP | Respiratory Viral Panel |
| RVVC | Recurrent VulvoVaginal Candidiasis |
| RWE | Real World Evidence |
| RWH | Red Wine Headache |
| RXR | Retinoid X Receptor |
| RXR | ReXinoid Receptor |