| Siggs | L. O. | Mildenbrook, Collie | 1OS | 1962 |
| Sigley | J. | Mount Stuart, Holt Rock via Newdegate | SG4 and 22B, 105A | 1962 |
| Sikirich | M. | 2071, 450 2070, Manjimup | MS2 and 8B, 13E | 1962 |
| Silbert & Sharp | - | Leonora (Carriers between Leonora and Wiluna) | QA7 | 1924 |
| Silchinger | L. | Kitchkoola, Goomalling | 9LS | 1912 |
| Silchinger | L. | Kitchhoola, Goomalling | 9LS | 1924 |
| Silcock | C. F. | Hillside, Walkaway | 6SK and 24B, 30A | 1962 |
| Silcock | C. J. | Pine Grove, Muchea | 4ZS and 42B, 103A | 1962 |
| Silcock | G. J. | Treasure Valley, Walkaway | 2NS and 53F, 109D | 1962 |
| Silcock | J. & G. | Bradley Siding, Greenough Flats | US2 | 1912 |
| Silcock | J. & G. | Bradley Siding, Greenough Flats | US2 | 1924 |
| Silcock | J. H. | Fitzgerald Loc. 500, Sunrise Hill, via Salmon Gums | Q6Z | 1925 |
| Silcock | J. W. | Kilarney, Walkaway | JS9 and 11C, 12E | 1962 |
| Silcock | Joseph | Hillside Farm, Walkaway | 6SK | 1912 |
| Silcock | Joseph | Hillside Farm, Walkaway | 6SK | 1924 |
| Siles | T. | Wiluna | 4XS | 1924 |
| Silinger | L. J. & B. J. | Silver Hill, Uearty, Goomalling | SQ6 and 32B, 7A | 1962 |
| Silke | A. D. | Quinninup, 3689, 662, Marybrook via Bussleton | D3S | 1962 |
| Sillifant Bros | - | Thurdon, Esperance | R0S and 22C, 25A | 1962 |
| Silsbury | E. G. | Avon Locs. 15257-8 and 18119, Kellerberrin | 5SK | 1912 |
| Silsbury | E. G. | Avon Locs. 18119 and 15257-8, Kellerberrin | 5SK | 1924 |
| Silva | D. W. | Windemere Est., Howatharra | DZ2 | 1924 |
| Silver | George M. | Locs. 1284, 1293/64, Ballidu | G8Z | 1924 |
| Silver Estate & Hood | - | Ardoch, Ballidu | G8Z and 15D, 27E | 1962 |
| Silver Pur | - | 3750, Hill River via Badginggarra | SF2 and 116B, 13A | 1962 |
| Silverthorne | G. R. | Glenrowen, Margaret River | 9ZP and 107D, 103E | 1962 |
| Silverthorne | L. A. | 2828, 2831, Margaret River | 0ZS and 4C, 9E | 1962 |
| Silvester | F. V. | 8957-8, 9420-2, Pemberton | SZ4 | 1962 |
| Silvester | H. W. | 1725, Cowaramup | YK9 | 1962 |
| Silvester | J. T. & B. | 1352, 91 pt. 927, 895, Bullsbrook | T2B and 112D, 18E | 1962 |
| Silvester | W. R. | Hambledon, Mt Barker | 0SF | 1962 |
| Sim | E. D. C.H & M. D. | Kurrara Park, Highbury | 3ES and 28D, 67E | 1962 |
| Sim | J. D. | Braidwood, Cranbrook | SJ0 and 4D, 67E | 1962 |
| Sim | J. P. & H. M. | Balintore, Kojonup | J1S and 37B, 114E | 1962 |
| Sim | P. D. | Waikopia Farm, East Highbury | S9D | 1924 |
| Sim | W. | Hazelwood Farm, Mt Many Peaks via Albany | SW4 and 33D, 24E | 1962 |
| Sim | W. W. R. | Hazel Farm, Albany | 9MS | 1962 |
| Sim Bros. | - | Maroondah, Kirk Rock via Wickepin | 4BS | 1912 |
| Sim Bros. | - | Maroondah, Kirk Rock, via Wickepin | 4BS | 1924 |
| Simam | - | Onslow Creek Station, Carnarvon | S2N | 1912 |
| Simcock Bros. | (A. & E.) | Nelson 3947, 5250, 8499, 1867, 5251, 11341, Manjimup | S3P and 14B, 71E | 1962 |
| Sime | A. | Fitzgerald Locs. 202, 449, 450, Circle Valley, Esperance | Y3Q | 1924 |
| Sime | A. | Glen Eden, Truslove | C4L and 14D, 110E | 1962 |
| Sime | K. A. | Esperance and Fitzgerald 144, 527, 1426-76-97,883-4, Truslove, via Collgardie | KS5 and 41D, 50E | 1962 |
| Sime | Robt. | Fitzgerald Loc. 207, Circle Valley | NY7 | 1924 |
| Simkin | Annie M. | Googililla Plain, Binnu | 2SQ | 1924 |
| Simkin | H. | Googalili Farm, Yuba via Northampton | SY3 | 1912 |
| Simkin | H. | Googililla Plain, Yuba | SY3 | 1924 |
| Simkin | Joseph W. E. | Victoria Locs. 8273, 4257, 4259, Binnu | W5A | 1926 |
| Simkin | K. A. | Googoolili, 4539-40, Binnu | SY3 and 35B, 29A | 1962 |
