- reticulin
- retinal, retinene
- retinoic acid
- retinyl palmitate
- reverse transcriptase
- reverse transcription
- reversed phase chromatography
- rhamnose
- rhodanese
- rhodopsin
- ribonuclease, RNase
- ribonucleic acid
- ribonucleoprotein, RNP
- ribose
- ribosomal RNA, rRNA
- ribosomal subunit
- ribosome
- ribosome binding site, RBS
- ribosylation
- ribulose
- ricin
- ricinoleic acid
- rocket immunoelectrophoresis
- rotatory dispersion
- S-adenosylhomocysteine
- S-adenosylmethionine
- saccharic acid
- saccharopine
- salmin
- salting out
- salvage pathway
- salvelin
- satellite DNA
- scleroprotein
- sclerotin
- scombron
- scorpion toxin
- scotopsin
- second messenger
- secondary structure
- secretin
- secretinase
- secretory piece
- thiolase
- thiouracil
- threonine, Thr
- threose
- thrombin
- thrombosthenin
- thromboxane