In a letter to the municipality, the chamber cited two major events --the Royal Show and Art in the Park -- being hosted on the same weekend.
Pietermaritzburg does not have sufficient accommodation to cater for visitors attending the three events, the chamber said.
From 1962 to 1994 the race was run on May 31, which was a public holiday under the old regime. It was moved to June 16, Youth Day, until 2007.
After calls from the ANC Youth League for the race date to be changed because of the political significance of June 16, the marathon has not been run on a fixed date. This year it was scheduled for June 1.
"Moving the Comrades back into this period has created what can only be termed as an accommodation crisis. Pietermaritzburg simply cannot accommodate Comrades runners as well as Royal Show exhibitors," PCB CEO Melanie Veness said.
She said marathon runners would find themselves inconvenienced by having to go to Durban to find accommodation. As a result, Pietermaritzburg would lose most of the economic spin-off from the Comrades Marathon.
"I am sure that the logistical implications involved in changing the date of such a major event are massive. I do not make this request lightly and wouldn't do so unless the situation was dire enough to justify it," she said.
The matter is set for further discussion by the Msunduzi municipality, which would make a decision on whether or not to support the PCB's appeal.