Businesses starting with S
- Siam Gumed Tape Co., Ltd.
- Siam Gypsum Industry Co., Ltd.
- Siam Gypsum Plaster Co., Ltd.
- Siam Hand Made Co., Ltd.
- Siam Hand Made Co., Ltd.
- Siam Hand Made Co., Ltd.
- Siam Hands Co., Ltd.
- Siam Hardware Industry Co., Ltd.
- Siam Hat And Cap Co., Ltd.
- Siam Herb Export Co., Ltd.
- Siam Heritage, The Co., Ltd.
- Siam Hermetic Co., Ltd.
- Siam Hi-tech Steel Center Co., Ltd.
- Siam Hitashi Automative Products Co., Ltd.
- Siam Hotel
- Siam Hotel Ltd., P.
- Siam Household Products (1979) Co., Ltd.
- Siam Ice & Cooling Co., Ltd.
- Siam Ikk Co., Ltd.
- Siam Industrial Corporation Co., Ltd.