HRI Chairman Brian Hartery said of the new measures, "These are unprecedented and sombre times and we are seeking the best ways to support the racing community and industry throughout what lies ahead".
Racing in Ireland is set to continue behind closed doors despite coronavirus and after fixtures in Great Britain were suspended until the end of April.
These meetings were subsequently reviewed by the HRI board and more measures have been implemented in response.
There will be no evening meetings and no double meetings - this will reduce the draw on medical resources, a principal concern for larger racing jurisdictions with multiple meetings every day.
A maximum of one meeting per day to reduce impact on resources.
The riders' weights will also increase by 2 pounds from Friday, with all racecourse saunas closed, and a maximum of 30-minute intervals between races to aid social distancing.
No owners permitted to attend race meetings.
No overseas runners will be permitted for the time being in Irish races.
"Race courses by their nature offer opportunities for social distancing that few other workplaces can".
"This will be kept under review on a daily basis and we are also planning measures to reprogram the accessories as necessary. Changes to the schedule will be announced separately".
A meeting of the Board of Horse Racing Ireland agreed this afternoon that race meetings in Ireland would continue to be held in strict adherence to Government guidelines regarding Covid-19 and staged without members of the general public.
"We have consulted with the Department of Agriculture, Food and the Marine throughout this process and we will continue to strictly adhere to the Government and HSE advice".
A scene from Kilbeggan Races a number of years ago. "Strict measures were imposed on them nearly immediately last Friday but their actions, care and vigilance have ensured that social distancing is being observed and racecourses continue to be a safe working environment".