One in five professional rugby union players in England suffered concussion during the 2018-19 season, according to the latest medical figures released by the Rugby Football Union (RFU).
The frequency of concussions -- measured by the number of incidents per 1000 hours of playing time -- is the second highest it has ever been.
The highest recorded concussion incidence was 20.9 per 1000 hours in 2016-17.
The figures come in the wake of several former players taking legal action against World Rugby, the RFU and the Wales Rugby Union (WRU).
The basis of the claim made on behalf of the nine test cases -- legal firm Rylands Law say they were talking to more than 130 more retired players -- is the sport's governing bodies failed to provide sufficient protection from the risks caused by concussion.
The RFU figures state that in 2018-19, 20.4% of players sustained at least one match concussion -- an increase from 16% in the 2017-18 season.
The report analysed 407 games and 763 players from 12 Premiership clubs.
For the eighth consecutive season, concussion was the most commonly reported match injury.
In total, there were 166 match concussions and 38 training concussions.
However, the report said the upside was the introduction of the real-time pitch-side video system in the Premiership enabled medical staff to identify more head injuries in 2018-19.
"Improving the detection of these complex injuries to ensure safe removal of concussed players remains a priority, as is developing and evaluating strategies to reduce concussion incidence," it said.
The Rugby Football Union and Premiership Rugby recommend seeking specialist neurological opinion following a second diagnosed concussion during a 12-month period.
The sport was rocked when England's 2003 World Cup-winning hooker Steve Thompson revealed earlier this month he could not remember the memorable moment in Sydney.
The 42-year-old was diagnosed with early onset dementia and probable CTE (chronic traumatic encephalopathy) in November.
"Knowing what I know now, I wish that I had never turned professional," he said.
"I went from working on a building site and training twice a week to training every day, sometimes twice a day.
"It was not uncommon for me to be left dazed, seeing white spots and not knowing where I was for a few seconds.
"Sometimes I would pass out completely. It was just an accepted part and parcel of training."
World Rugby chairman and former England captain Bill Beaumont had to retire from the sport due to successive concussions but he said the link between concussion and brain injuries is complex.
"It is clear the area of concussion and long-term cognitive health is extremely complex," he wrote last week.
"We have continuously acted on research and scientific information as it has become available.
"The science continues to evolve, and we will evolve with it."