Four-year-old Serenity Straker came home from "Little Inventors Day Care" in the Bronx last week and showed her mom small capsules of the white substance.
Serenity says another child at the school gave them to her.
Serenity's mom called police, who confirmed it was crack cocaine.
Serenity was rushed to a local hospital.
"She couldn't sit down. She was beyond bouncy, very loquacious, just all over the place, literally, talking to herself, looking in the mirror, saying she sees three of herself. Once they did the urine test, it came back positive that she had cocaine in her system," said Sabrina Straker.
Daycare officials believe someone threw the drugs over the school's fence to get rid of it.
Police are looking into potential child endangerment charges.