Many nurses have reportedly stayed away from the main hospitals in Harare and nearby Chitungwiza in an indefinite protest over pay and conditions.
Last week, army doctors were brought in to help cope with the doctors' strike.
The BBC's Shingai Nyoka in Harare says Zimbabwe's medical professionals are some of the worst paid in the region and their salaries are often paid late.
Hospitals have been turning away the sick and patients have been discharged early following a doctors strike over allowances and job security.
There is a concern that army personnel brought in as a stop-gap will not be able to cope without nurses.
The nurses' main demand is that the government honours its commitment to pay out 2016 bonuses.