The number of new complaints was down 4.5% compared with 2017/18 - and slightly below the figure for 2016/17, data from NHS Digital show.
Complaints upheld are also at a three-year low, with just 34.4% upheld in 2017/18 compared with 36% the year before - and 37.1% in 2016/17. Complaints partially upheld, however, rose from 14.5% in 2017/18 to 16.5% in 2018/19.
The figures confirm that just a tiny proportion of patient contacts with general practice result in a complaint. Patient survey data released this year also reflected high levels of satisfaction, with 83% of patients satisfied overall with their GP service.
Compared with the 308m appointments delivered in general practice in 2018/19, the figures show that practices receive a written complaint for one in every 4,200 appointments. However, the complaints may in fact relate to any form of contact with a GP practice, such as a phone call or conversation with a member of reception staff - meaning that an even lower proportion of appointments themselves are responsible for a written complaint.
The most common reason for a complaint about general practice in 2018/19 related to 'communications', with complaints about 'clinical treatment the second most common at 12%.
Waiting times for a GP appointment - a major focus of government policy and something prime minister Boris Johnson pledged to reduce in his first speech in the role - accounted for just 3% of written complaints in 2018/19 - down from 3.2% the previous year and from 3.7% in 2016/17.
However, 9.3% of complaints related to 'appointment availability/length' - a figure higher than in either of the previous two financial years, suggesting that access to appointments may be a growing concern.
Family Doctor Association chair Dr Peter Swinyard told GPonline that the overall drop in written complaints for general practice was 'impressive' and demonstrated that practices were continuing to perform to a high level 'whatever the pressures on them'.
He said suggestions that availability of appointments may be in decline related to the 'simple maths of supply and demand', with a GP workforce in decline caring for an ageing population. He warned that general practice 'suffered' as a consumer-facing service by comparison with, for example, online shopping services that make the public expect 'everything to be available immediately'.
'We don't have the resources for that - at the moment the NHS is funded to cope with patients' needs, not their wants,' Dr Swinyard said.
He added that the figures showed that practices were 'not doing too badly', adding: 'It is important to take positives from this and say that although we don't want any complaints, in proportion to patient contacts this shows the general level of service is very acceptable.'