The Broadway, in Bournemouth, advertised the event offering free shots to ‘deranged doctors and nurses’.
The “Broadway Mental Asylum" event has been labelled a damaging stigma, with a mental health blog claiming it is demonising to patients.
But Greene King's cancellation of the event and apology led to a debate on social media.
Many condemned the pub:
The venue’s pubco Greene King apologised for the unsanctioned event.
The manager of the pub apologised, and said the pub acted promptly to complaints.
A Greene King spokesman added: 'We apologise for any offence caused by the poster at the Broadway pub. This was not part of a wider Greene King initiative and was removed as soon as it was brought to our attention.
'It should never have appeared and we will be working with the team on additional training to make sure this cannot happen again.
'We would like to reiterate that Greene King takes diversity extremely seriously across the business and our pubs and restaurants offer a welcome to all.'
What's a great pub theme for Halloween? Send your ideas to oli.gross@wrbm.com