| 2812 | Septic tanks, heavy gauge metal, manufacturing | |
| 2520 | Septic tanks, plastics or fibreglass, manufacturing | |
| 2695 | Septic tanks, prefabricated concrete, manufacturing | |
| 3312 | Sequencing controls for electric heating equipment, manufacturing | |
| 3210 | Series capacitors (except electronic), manufacturing | |
| 8519 | Serological services, blood bank laboratory | |
| 1410 | Serpentine, crushed and broken stone, quarrying | |
| 1410 | Serpentine, dimension-quarrying | |
| 2423 | Serums (except diagnostic substances), manufacturing | |
| 8030 | Service academies (college) | |
| 4530 | Service and repair of broadcasting stations, contractors | |
| 1810 | Service apparel, washable (e.g., maids', nurses', waitresses'), women's, misses' and girls', made from purchased fabric | |
| 1810 | Service apparel, washable, men's, cut and sewn from purchased fabric | |
| 7230 | Service bureaus, computer | |
| 5150 | Service entrance equipment, electrical, wholesale | |
| 9111 | Service industries associations | |
| 5150 | Service industries machinery and equipment, wholesale | |
| 8532 | Service leagues | |
| 4520 | Service lines, gas and oil, construction | |
| 5110 | Service machinery and equipment, wholesale agents and brokers | |
| 5050 | Service station (gasoline, lubricating oils and greases), retail | |
| 7493 | Service station cleaning and degreasing service | |
| 5150 | Service station equipment and supplies, wholesale | |
| 4530 | Service station equipment installation, maintenance and repair, contractors | |
| 4530 | Service station pump repair | |
| 4520 | Service stations, construction | |
| 1120 | Service well drilling, on a contract basis | |
| 0140 | Services incidental to agricultural crops, unspecified | |
| 7499 | Services to publishers (invisible publishers) | |
| 7010 | Servicing of raw land for subsequent sale | |
| 1120 | Servicing oil and gas wells, on a contract basis | |
| 4520 | Servicing water wells, contractors | |
| 6303 | Servicing, aircraft (at airport) | |
| 2109 | Serviettes, paper, made from purchased paper | |
| 3610 | Serving carts, household, metal, manufacturing | |
| 3110 | Servomotors, manufacturing | |
| 7499 | Set design, theatrical (except independent) | |
| 9214 | Set designers, independent | |
| 4520 | Setting reinforcing bars or rods, construction | |
| 8532 | Settlement houses | |