Parasitic worm, also known as helminth, is large macroparasite.
Parasitic worm may also refer to:
- Acanthocephala, or the spiny-headed worms all of which are parasitic.
- Hirudinea, extoparasitic annelids commonly known as leeches
- Nematoda, or roundworms the most well known of which are parasitic
- Pentastomida, sometimes referred to as tongue worms which are obligate parasites
- Platyhelminthes, or flatworms the phyla which contains the parasitic tapeworms and flukes.