I often find myself asking this question whenever the topic of the fire comes up.
You hear about the devastation, the rebirth, the cow, but rarely do you ever hear about victims. That omission just doesn't fit with how Americans tend to relate to disasters, including historic ones.
For instance, doesn't it seem like there would have been some notable memorial for the victims of the fire erected by now given the great standing this event has in our city's history?
Or, if there were no victims, isn't that a remarkable aspect of the fire that's worthy of greater attention?
The Newberry Library took a stab at answering the question in 2003. Basically, they don't know how many. Maybe about 300. Their remains were probably left and built over. You can find the full explanation here.
[I just stumbled across this photo of a recent memorial statue erected at the site of the (supposed) start of the fire.]
Photo courtesy of the Chicago Landmarks Commission here.