About 400 people have carried out a peaceful protest against the work of Huntingdon Life Sciences.
Huntingdon Life Sciences has been targeted by protest
This is the first local protest against the animal testing laboratory in four years, Huntingdon police said.
The group was escorted around Huntingdon town centre and its ring road by police.
Chief Inspector Darren Anderson said this was to protect the group's right to protest and to ensure any lawful employment was not affected.
The demonstrators later went to Huntingdon Life Science's laboratories at nearby Woolley where organisers Stop Huntingdon Animal Cruelty held a rally.