| ABC | 1991 | Specialised Languages | Sound-Performance | United Kingdom | |
| Andorra-I | 1991 | Specialised Languages | United Kingdom | Bristol U Andorra | |
| CPL | 1991 | Specialised Languages | United Kingdom | Categorical Programming Lanugage | |
| Duration Calculus | 1991 | United Kingdom | |||
| ELSIE | 1991 | United Kingdom | |||
| Gofer | 1991 | United Kingdom | |||
| Lucinda | 1991 | United Kingdom | |||
| Megalog | 1991 | United Kingdom | |||
| Miracula | 1991 | United Kingdom | |||
| NUA-Prolog | 1991 | String and List Processing | Horn clause | United Kingdom | Extension to the WAM for Parallel Andorra |
| Pascal-Linda | 1991 | Multi-purpose | Pascals | United Kingdom | |
| Pi Calculus | 1991 | United Kingdom | |||
| PICT | 1991 | United Kingdom | |||
| Quintec Prolog | 1991 | String and List Processing | Horn clause | United Kingdom | |
| Quintec-Objects | 1991 | United Kingdom |