Businesses starting with S
- Siam Fine Chemicals Co., Ltd.
- Siam Fine Clay Co., Ltd.
- Siam Firework Co., Ltd.
- Siam First Pack Ltd., P.
- Siam First Rice Co., Ltd.
- Siam First Tour Co., Ltd.
- Siam Floor Tile Co., Ltd.
- Siam Flour Trading Co., Ltd.
- Siam Flower Co., Ltd.
- Siam Flowers (1985) Co., Ltd.
- Siam Fluorescent Lamp Co., Ltd.
- Siam Food Co., Ltd.
- Siam Food Products Plc.
- Siam Food Supply Co., Ltd.
- Siam Foods Express (thailand) Co., Ltd.
- Siam Foundry Ltd. P.
- Siam Friend Fishing Products Co., Ltd.
- Siam Fugs Lubricants Co., Ltd.
- Siam Fuji Ware (1988) Co., Ltd.
- Siam Furukawa Battery Co., Ltd.