New information means that the cases against three people accused of ill-treatment of people Penzance's John Daniel Day Care Centre have been dropped.
The centre cares for over 80 people with learning difficulties at a care home in Cornwall.
Philip Sowden, 60, of Penzance, Christine Keller, 59, of Hayle and Benjamin Jenkins, 23, of St Ives, had denied all the charges.
The Crown Prosecution Service offered no evidence at Truro Crown Court.
Nicola Haywood, of the Crown Prosecution Service (CPS), said: "When we initially reviewed this case we felt there was sufficient evidence for a realistic prospect of conviction.
"The CPS has a duty of continual review and, as part of this process, information came to light which meant there was no longer a realistic prospect of conviction."
Cornwall Council said: "The council will continue to work closely with partners and people who use the service and their families to ensure high quality and safe service provision."