Residents in the neighborhood say there are usually 70 to 80 people waiting in line to get into the clinic and that the line often goes all the way around the block.
A spokesperson for the Drug Enforcement Administration confirmed that DEA agents were at the Midtown Medical Clinic located in the 4500-block North Sheridan Road.
The agents blocked off the area and no one was allowed in or out of the clinic.
ABC7 sources said that the warrants have been served regarding the distribution of pain killers.
One patient who came back to see the doctor who runs the clinic was not allowed in.
The patient did not want to be identified, but said he is a legitimate patient and the doctor has been treating him for a leg injury.
"We knew a lot of them were shady just by the way they appeared coming in, bringing in five or six people at a time, they come in like groups. I have never seen anything like that. I have seen over 80 people standing out here to get in while the lobby is full," he said.
The patient says he has a hard time finding a pharmacy to fill out the doctor's prescriptions and that is why he came back Thursday to get his money back.
He claims that the doctor charged him $75 a visit and that in January he raised his fee to $230 a visit.
At around 2:30 Thursday afternoon DEA agents started bringing out several boxes labeled "DEA evidence" and began putting them inside a van.
Inside, the agents could be seen taping up more boxes of evidence and bringing them out. So far, they have brought out 20 boxes of evidence.
Chicago Police and Internal Revenue Service agents are also on the scene.
DEA agents have also been coming in and out of the door of an apartment building connected behind the clinic.