The Irish Medical Organisation has begun a ballot of its 2,000 non-consultant hospital doctor members for support for action to reduce long working hours.
The result of the ballot will be known on 2 September.
IMO Assistant Director of Industrial Relations Eric Young said it was unsafe to have doctors working straight shifts of 24 hours and longer.
The IMO wants the Health Service Executive to fully implement the European Working Time Directive, which limits working time to no more than 48 hours a week.
Minister for Health James Reilly has told the European Commission that this will be in place for NCHDs by the end of 2014.
There are over 4,800 NCHDs in the health service.
Speaking on RTÉ's Morning Ireland, Mr Young said: "Doctors might start working at 9am, work right through to 9am the next day and then do a full day's work before they can go home.
"It's not safe for patients, it's putting them at risk in terms of the administration of drugs, prescriptions that are being issued, records that are being kept on patients and obviously it impacts on patient safety."
In the event of strike action, he said, it is hoped that patient care would not be affected.
"Normal cover will be provided but it may involve clinics and elective work may be affected, so it may have some short-term implications."
Any possible action could involve work stoppages by junior doctors, he said.
"If that is not successful and we don't get sufficient progress we will have rolling national action throughout the country."