The increasing demand for his services, a relapse in his drug addiction, and his ill health combined to strike Efraín in the peak of his popularity. He died on March 12, 1978 in Manhattan, New York City, of a heart attack. He was soon buried in Mayagüez's Old Municipal Cemetery, gathering the second largest funeral crowd assembled in the city, second only to that of the 1993 burial procession for Benjamin Cole, the longest-serving mayor in the city's history. An impromptu plena band played his songs during the walk between the religious service and his burial place.