More than a third (38%) of respondents reported they still do not evaluate their events and 26% of those that do have no idea what return they are getting.
The study, completed by research firm RSM, sampled directors and managers at 100 blue-chip companies evenly distributed between five sectors: automotive, banking and finance, oil and gas, information communications and telecom (ICT) and pharmaceuticals. The respondents included BT, Credit Suisse, Ford and Toyota.
A comparison found that the ICT sector places the greatest emphasis on event activity. It is also the sector most inclined to evaluate the return on investment.
Chris Hill, joint managing director of McMenemy Hill, said: "In light of these findings, which reveal some significant shortcomings in event management, our confidence is strengthened that a more strategic approach will help many companies make a substantial improvement in what they do and the outcomes they achieve."
The report also found the average annual event spend is £600,000, with the pharmaceutical and oil and gas sectors being the biggest spenders.
Despite this, only 52% of companies reportedly produce an annual event plan.
McMenemy Hill commissioned earlier research into the sector in 1999.
In comparison, the management priority events receive is unchanged, despite increased investment in the sector.
As a follow-up, the agency now plans to arrange a seminar in which companies can better evaluate the performance of events and examine best practice.