GP members made 517 complaints in 2007 and 2008 compared with 337 in the previous two years.
Out-of-hours complaints now represent 10% of the annual total of complaints compared with 8% in the previous two years.
Dr Stephen Green, head of risk management at the MDU, said: ‘Compared with the many millions of patients who are seen out-of-hours each year, the number of complaints notified to us by our members is small.
‘However, out-of-hours care continues to represent a significant and growing proportion of the complaints we see.
‘We are advising out-of-hours doctors to pay particular attention to the need for clear, unambiguous communication with patients and colleagues, including accurate and comprehensive note-taking and arranging follow-up if necessary.'
Prior to the new GMS contract the MDU only has comparative figures for 2002 when there were 120 complaints.