The Medical Laboratory Workers Union has begun re-issuing notices for partial industrial action in Christchurch.
Lab workers are engaged in full and partial withdrawals of labour at 13 district health boards and the New Zealand Blood Service over pay.
The union suspended action in Christchurch the fourth because of the earthquake on 4 September, but resumed issuing the notices on Tuesday.
Union president Stewart Smith says partial industrial action will take place at Christchurch hospitals and labs from 6 - 12 October.
Some telephone work and non-clinical lab tests will be affected.