70% more complaints were made at Crumlin Hospital last year compared to 2014.
A freedom of information request published in The Herald shows over 1,000 formal gripes were lodged.
The failure to provide safe and effective care at the hospital was the basis for 300 complaints. They included misdiagnosis, poor hygiene, mislaid sampled and pest control issues.
Almost one in four related to access including overcrowding, the use of restraint and delays with admissions and appointments.
274 were about issues in communication. HSE guidelines say that can include inappropriate comments about staff and a failure to listen to the patients.
The hospital received 19 complaints about dignity and respect and 38 on accountability.
Overall, the hospital received 1,029 complaints last year. That number is up from 608 in 2014.
Compliments or instances of positive feedback also fell last year from 239 in 2015 to 202.