"There have been a lot of changes to the lab since I started in 1972. It has had four of five makeovers with the latest only recently completed as part of the building and redevelopment programme at the hospital."
Attendants' manager Steve Coles called Dennis one of the few remaining 'real characters' of the hospital in a tribute.
"He would be the man you would keep an ear out for (as you would hear him before you saw him) if there was a cricket match happening, so he could give you the latest score update," wrote Coles.
"In my earlier years in the organisation, the attendant service played many a cricket match against the 'rest of the hospital', and Dennis was always ready to lend some advice on the correct batting stance, and would then proceed to imitate Ken Rutherford.
Mr Coles says it is always a positive experience to run into Dennis in the hospital corridors - unless the Black Caps had failed - as he is always happy to have a bit of banter.
"We look forward to many more years of his good humour, good looks and good commentary."
Hospital business services manager Melinda Ch'ng calls Dennis a hospital icon .
"Nothing is ever a problem and he is a very a loyal and reliable staff member."
Dennis is the fourth Waikato Hospital attendant to celebrate 40 years of service in the past 12 months.