The average salary of chief executives in the UK is still 117 times more than the average worker, despite seeing a 13% fall last year.
Professional HR body, CIPD, found that the average salary for top bosses fell to £3.5 million in 2018, compared with the average salary of £29,574 for full-time workers in the UK.
It also found a disparity in gender pay, with the number of female chief executives on the FTSE 100 falling from seven to six.
CIPD chief executive Peter Cheese said: "The gap between pay at the top and bottom of firms remained "unacceptably wide".
"We must question if CEOs are overly focused on financial measures and are being incentivised to keep share prices high rather than focusing on the long-term health of their business."
Luke Hildyard, director of the High Pay Centre, which analyses executive pay with CIPD, said: "There is still more to be done to align pay practices with the interests of wider society.
"[It's important to] give the public confidence that our biggest businesses are working for the good of the economy as a whole, rather than the enrichment of a few people at the top."
The organisations published a number of recommendations, including disclosure of pay for the top 1% of earners. They also call for wider understanding of workplace culture and investment in people development, while also recommending executive pay and rewards are simplified.
Frances O'Grady, general secretary of the Trades Union Congress (TUC), said: "It would take most workers two lifetimes to earn what top execs get in a single year. That's not right.
"This shocking pay gap won't change without major reform. We need new rules to give workers seats on executive pay committees. This would help bring some much-needed common sense and fairness to boardroom pay."
And GMB union general secretary Tim Roache said: "It's an absolute scandal the average worker will have to graft for more than a century to earn the same pay a CEO gets in just a year.
"GMB has never been against people getting well paid for doing a good job - but we need a maximum pay ratio enshrined in law to keep our society fair and healthy."