Race results
Race 1; 1955 Southern 100 Junior 350cc Race final standings.
July 1955 Billown Circuit 12 laps – 51 miles (81.13 km)
| Rank | Rider | Team | Speed | Time |
|---|---|---|---|---|
| 1 |  Derek Ennett | 350cc AJS | 76.79 mph | 39' 51.27 |
| 2 |  Dave Chadwick | 350cc Norton | 76.75 mph | 39' 51.87 |
| 3 | Dennis Pratt | 350cc BSA | — | +1 lap |
| 4 | Dennis Christian | 350cc BSA | — | +1 lap |
| 5 | Edward Hunt | 350cc Velocette | — | +1 lap |
| 6 | P.H.Beighton | 350cc AJS | — | +1 lap |
| 7 | V.L.Green | 350cc AJS | ||
| 8 | John Holder | 350cc BSA | ||
| 9 | D.E.Burns | 350cc BSA | ||
| 10 | T.H.Anyon | 350cc BSA |
Race 2; 1955 Southern 100 Lightweight 250cc Race final standings.
July 1955 Billown Circuit 6 laps – 25.50 miles (41.06 km)
| Rank | Rider | Team | Speed | Time |
|---|---|---|---|---|
| 1 | Dave Chadwick | 250cc RDS | 65.50 mph | 23' 21.0 |
| 2 | John Patrick | 250cc Velocette | 63.70 mph | 24' 00.0 |
| 3 | Frank Cope | 250cc Norton | 63.26 mph | 24' 11.0 |
| 4 | Dougie Rose | 250cc Velocette | 61.30 mph | 24' 57.0 |
| 5 | Syd Mizen | 250cc Francis-Barnett | 58.80 mph | 26' 01.0 |
| 6 | K.R.E.Prince | 250cc Francis Barnett | — | +1 lap |
| 7 | D.Rumble | 250cc CTS | — | +1 lap |
Race 3; 1955 Southern 100 Solo Championship 500cc Race final standings.
July 1955 Billown Circuit 24 laps – 102 miles (164.25 km)
| Rank | Rider | Team | Speed | Time |
|---|---|---|---|---|
| 1 | Terry Shepherd | 500cc Norton | 78.26 mph | 1:18.11.8 |
| 2 |  Alastair King | 500cc Norton | 75.50 mph | 1:21.01.0 |
| 3 | Derek Ennett | 500cc Matchless | 75.20 mph | 1:24.21.4 |
| 4 | Jack Wood | 500cc BSA | — | +1 lap |
| 5 | Brian Duffy | 500cc Norton | — | +1 lap |
| 6 | Eddie Crooks | 500cc Matchless | — | +2 laps |
| 7 | V.L.Green | 500cc AJS | ||
| 8 | John Holder | 500cc BSA | ||
| 9 | P.H.Beighton | 500c AJS | ||
| 10 | D.E.Burns | 500cc BSA |