Trainee medical staff and specialists didn't go into work on Wednesday in the southern region of Malopolska under the banner of "a day without doctors."
Some doctors also joined a hunger strike at a local hospital in Krakow, the region's largest city, in solidarity with colleagues around the country who have been protesting this month.
The doctors said in a statement on Wednesday that there was a shortage of doctors in Poland and that domestic medics have to go abroad for work. They demanded better working conditions, shorter hospital waiting lists and less red tape.
"There is a lot of money in the health service, but the government is telling us everything is going well, while patients are suffering," Grzegorz Siwek, a trainee from the University Hospital in Krakow told the daily Gazeta Wyborcza.
The doctors are also demanding an immediate pay rise to 105 percent of the national average monthly wage of 4,600 zloty (€1,010) gross each month. Resident doctors make between 3,000-3,5000 zloty gross a month.
Health Minister Konstanty Radziwill said on Tuesday that around 1.5 billion zloty (€350 million, $420 million) in extra funds would be injected into the national health service under an amendment to this year's budget.
He later condemned the strike, telling public broadcaster TVP1 that "one should not toy with the health and life of patients."
The strikers have the public's support, according to an opinion survey by the Ibris institute for the Rzeczpospolita daily, released on Wednesday, which said 63 percent of respondents backed the doctors' initiative.
On Wednesday only emergency rooms were open in hospitals in the Malopolska region, according to a statement by the union, OZZL, which said the one-day strike had been a doctors' initiative without union involvement.
Hunger striking doctors in the town of Prokocim sent out a message to support young doctors on Wednesday:
The strike follows several protests in the public sector against the government since it came to office in late 2015, promising higher health care spending.
The dispute started on October 2 when a group of 20 resident doctors started a hunger strike in the foyer of a Warsaw pediatric hospital. This was later repeated in other big cities. On October 14, 1,000 medical professionals rallied in the capital.
The doctors are demanding higher salaries and an increase in public health care spending across the board. They want the conservative Law and Justice (PiS) party government to increase health care spending to 6.8 percent of GDP within the next three years.
The health budget for this year is 4.7 percent of GDP.
The government adopted a draft bill on Tuesday that would see a gradual increase in the health budget to 6 percent of GDP - the World Health Organization recommended level - but not until 2025. Protesters are demanding that the government make these reforms sooner.
Polish inflation was at 2.2 percent in September, with the government keen to maintain spending limits in the public sector to sustain this relatively low level of price growth.