Rows of beautiful, old homes are vacant -- some boarded up and others sealed with concrete.
Instead of making patients from this impoverished side of town come to him, the doctor goes to them.
"It's who I am," Katz says. He's mimicking how his father used to operate -- carrying a medicine bag and pounding the pavement to make house calls. It's old-school medicine with new technology.
"There (are) things that happen to me in my life that created commitments -- growing up in a medical family, personal tragedies. ... Anybody who is sick, I'm connected to," he says.
Getting out of his car with his medical bag, he walks into the home of the day's first patient, Brandon Thomas.
"You're going to feel just weak until these things get fixed," Katz tells Thomas, 26, who is a paraplegic.
"I had got shot in the back walking to my car," he says. Now, he has an infection. He lies on his bed with his legs exposed. They are atrophied. He has a large bandage on his hip.
Thomas is on a host of medications and needs a plethora of medical supplies. He also has to worry about where he's going to get what he needs.
"It's pretty hard," Thomas says as he lies on his bed watching TV.
Things got worse as a result of the recent riots near his Baltimore neighborhood
in the aftermath of the death of Freddie Gray
while in police custody.
Looters picked off pharmacies. At least a dozen were ransacked, broken into or burned. Those actions hurt Baltimore's most vulnerable -- the sick and the elderly.
"They hurt their own neighborhood, and that's the hard part about it ...," says Velma Moseley, who has to take a bus to find the medications she needs. "We're a close-knit neighborhood. We help one another. But we can't even help each other. No supermarket, no medicine. Even the corner store was tore up."
Moseley is in a wheelchair at a bus stop about 25 feet from a neighborhood mom-and-pop pharmacy that is boarded up. There are bullet holes in its window, and its shelves are wiped almost clean. Pill packets lie on the grass out back. They are all empty.
The loss of the pharmacies means prescriptions are harder to come by. Those taking pain medicine, for example, have an even harder time because such medications are tracked. Some of the pharmacies' computer systems were ruined, and if a prescription had already been filled, other pharmacies can't refill it.
"It created panic in the patients. They all have my cell phone number, so I got a lot of calls about, 'What am I going to do? Where am I going to go? Help me,' " Katz says. "It reduced their access to their necessary medications to stabilize their health."
Katz has been scrambling to find ways to get the right medicines to his sickest patients.
"We would die if Dr. Katz wasn't coming here. I don't know what we would do," says Rita Evans. Her son, Jesse, was also paralyzed also from a gunshot wound.
Without Katz's house calls, Jesse Evans says his life would be in constant turmoil.
"I trust this man. He's a very good doctor and a friend. I love him. I love him," Evans says. "The man saved my life."