"We did not want to strike and last week we started picketing, but we've since heard no word from management. This means that they are now taking us for granted," Hospersa's general secretary Noel Desfontaines said.
Workers from two hospitals in KwaZulu-Natal were protesting outside their hospitals by about 8.40am on Wednesday.
Workers from four other provinces were expected to join in the strike.
The union, representing nurses and administration workers, wanted a 12 percent salary increase while the company was prepared to pay 8.5 percent.
Affected hospitals were the N17 Hospital in Gauteng; St Augustine's, Parklands, Umhlanga and Alberlito hospitals in KwaZulu-Natal; Kyler and Greenacres hospitals in the Eastern Cape; Ferncrest Hospital in the North West; and Pelenomi and Kroonstad hospitals in the Free State.
Hospersa declared a dispute with Netcare management last week.