| RIS | radiology information system; rapid immunofluorescence staining; resonance ionization spectroscopy |
|---|---|
| RISA | radioactive iodinated serum albumin; radioimmunosorbent assay |
| RISC | reduced-instruction-set computer |
| RIST | Radio-Immuno-Sorbent Test |
| RIST | radioimmunosorbent test |