Dr. Olajide Williams, a Harlem brain doctor, is ready to show off his dance moves.

Having traded his white coat for a denim shirt, Dr. Williams makes his way to the front of a packed auditorium at a Harlem elementary school. As hip-hop music blares from a stereo, the Nigerian-born physician bounces up and down, simultaneously launching into a lesson about stroke prevention. “The greatest thing you can do for anybody is to save a life,” the 38-year-old neurologist and the director of Harlem Hospital Center’s stroke center tells some 200 third- and fourth-grade students at P.S. 46, the Arthur Tappan School.

By setting health lessons to a beat, Dr. Williams aims to instruct students in risk factors for strokes and to encourage them to call 911 if someone experiences one. Since its inception in 2005, more than 2,000 New York City students have participated in Dr. Williams’s “Hip Hop Stroke” program, which he developed with the National Stroke Association.

Sometimes called a “brain attack,” stroke occurs when the blood supply to the brain is cut off, either because of a clot or a burst blood vessel. An estimated 700,000 Americans suffer a stroke annually, and blacks are twice as likely to experience a stroke than whites. Nationwide, stroke is the third leading cause of death. A common disability among surviving patients is paralysis on one side of the body.

At the Harlem school, Dr. Williams quizzes the children on basic information, and they chant answers back at him: Where does stroke happen? Brain! What is a stroke? Brain attack! Stroke comes on how? Sudden!

He danced in the aisles as students swayed in time to a performance by the rapper Doug E. Fresh, who is a spokesman for the program. Halfway through the hour-long lesson last week, Rep. Charles Rangel, the longtime Democratic congressman from Harlem, addressed the group.

“Dr. Williams comes here with a very, very special program,” Mr. Rangel said. “He’s a doctor, he’s a specialist, he’s one of the smartest people we have,” he added, deviating from the program slightly with several references to heart attacks before returning to the risk of stroke.

Dr. Williams said a classmate at boarding school in England introduced him to hip-hop music in the 1980s, when the classmate played the LL Cool J song “I Can’t Live Without My Radio,” and told him, “Dude, you really need to listen to some real music.” At the time, he favored bands such as the Cure and Dire Straits. “That was my introduction to hip-hop, from a white English boy from London’s South End,” he said.

Dr. Williams said hip-hop is an ideal way to reach young people because its appeal crosses cultural lines. “Kids across the United States love it,” he said.

Born in Nigeria on Christmas Eve, Dr. Williams said his mother’s labor progressed too quickly to make it to a hospital, forcing his father, a physician, to deliver him with the help of an uncle. An asthmatic, Dr. Williams spent the first year of his life in and out of the hospital, and his parents wondered if he would survive.

He did, and went on to enjoy a “privileged education” in England, graduating from St. Martin’s School in Middlesex County and Haileybury College in Hertfordshire. At his father’s urging, he returned to Africa and received a medical degree from the University of Lagos.

During medical school, Dr. Williams said he struggled to find his identity and grappled with the contrast between his good fortune and the experience of poor Africans. “The reality of poverty was stark and vivid,” he said. “That gave me a new momentum to always try to reach out to those who are less fortunate,” he said.

After moving to New York in 1997, Dr. Williams earned his American medical credentials, completing an internship at Harlem Hospital and his neurology residency and fellowship at New-York-Presbyterian Hospital/Columbia University Medical Center, where he is currently an assistant professor of clinical neurology.

Dr. Williams said he has turned down lucrative positions to work in Harlem, where he lives with his wife, Buki, and their two children. “That’s where I feel I can make the most difference,” he said.

In 2005, Dr. Williams teamed up with the National Stroke Association to develop the Hip Hop Stroke program, which the association also runs in seven other cities nationwide. “He understands that starting with the youngest members and getting them on board early is a huge step in all of us being able to make a difference,” a vice president of the group, Diane Mulligan, said of Dr. Williams.

In New York, the program has received $25,000 from JP Morgan Chase, $25,000 from the Health and Hospitals Corporation, and additional funding from the speaker of the City Council, Christine Quinn.

Teaching children about strokes is meaningful since chronic illnesses affecting Harlem residents — diabetes, heart disease, and high blood pressure — all can lead to stroke, Dr. Williams said.

At least two children who have participated in the program called 911 after seeing someone experience a stroke, Harlem Hospital officials said.

Dr. Williams praised the partnership surrounding stroke awareness that has emerged among children, elected officials, and physicians. “Health shouldn’t be left to us doctors alone, or it is doomed to fail,” he said.