PTSI
| Acronym | Definition |
|---|---|
| PTSI | P.A.M. Transportation Services, Inc. (est. 1986; Tonitown, AR) |
| PTSI | Platinum Silicide |
| PTSI | Pupil Transportation Safety Institute (Syracuse, NY) |
| PTSI | Panhandle Telecommunication Systems, Inc. |
| PTSI | Philippine Tuberculosis Society, Inc. |
| PTSI | Pancreatic Secretory Trypsin Inhibitor (protease inhibitor) |