| 3511 | Ammonium sulphate manufacturing | |
| 3829 | Ammunition loading and assembling plant | |
| 3529 | Ammunition manufacturing, small arms | |
| 3829 | Amphibian military tanks manufacturing | |
| 3832 | Amplifier, audio-frequency, manufacturing | |
| 3832 | Amplifiers | |
| 9490 | Amusement concession operation | |
| 3420 | Amusement guide publishing | |
| 9490 | Amusement hall operation | |
| 9490 | Amusement park operation | |
| 3522 | Anaesthetic manufacturing | |
| 9331 | Anaesthetist, own account | |
| 3825 | Analogue computer manufacturing | |
| 8103 | Analyst, securities, own account | |
| 3851 | Analyzer for testing electrical characteristics manufacturing | |
| 3710 | Anchor, for mooring ships, buoys, etc., iron or steel, manufacturing | |
| 3114 | Anchovies | |
| 2902 | Ancient natural fertilizer gathering | |
| 2901 | Andalusite mining or quarrying | |
| 2901 | Andesite quarrying | |
| 2909 | Anhydrite mining | |
| 3511 | Animal black manufacturing | |
| 1110 | Animal breeding | |
| 1120 | Animal breeding on a fee basis | |
| 3115 | Animal fat rendering, excluding edible tallow and lard | |
| 9332 | Animal hospital | |
| 9332 | Animal humane society | |
| 3115 | Animal oil hydrogenating, excluding edible fats | |
| 3115 | Animal oil refining | |
| 3522 | Animal oil, medicinal preparation, manufacturing | |
| 3522 | Animal remedy manufacturing | |
| 3529 | Animal, vegetable and synthetic glue, except dental, manufacturing | |
| 3851 | Ankle support manufacturing | |
| 3710 | Annealing steel | |
| 3720 | Anode, electroplating, nickel, manufacturing | |
| 2100 | Anthracite mining | |
| 3852 | Anti-aircraft director, optical, manufacturing | |
| 3829 | Anti-aircraft gun manufacturing | |
| 3522 | Antibiotic, medicinal, manufacturing | |
| 3511 | Anti-freeze alcohol manufacturing | |