IT issues have led to the postponement of some hospital appointments and surgery at Leeds hospitals.
It is not known how many patients are affected by the IT gremlins but Leeds General Infirmary, St James's, Chapel Allerton, Wharfedale and Seacroft hospitals are all reporting issues.
It is understood that Leeds Teaching Hospitals Trust had been "experiencing some significant problems with the pathology IT system".
A spokesman advised that “If patients are worried they should contact their outpatient clinic, clinician or GP.”