There is no biographical information about Gaspar de Aguilar, author of the treatise Arte de principios de canto llano, nuevamente enmendado y corregido por Gaspar de Aguilar, con otras muchas reglas necesarias para perfectamente cantar. Dirigido al muy ilustre señor, don Pedro Manrique, obispo de Ciudad Rodrigo y capellán mayor de la capilla de los Reyes Nuevos de la santa iglesia de Toledo (from the early 16th century, without date and place of publication), of which a unique copy is found at the Biblioteca Colombina in Seville. 

Polyphonic works atrributed to "Aguilar" in El Escorial and the Capilla Real in Granada are most likely by Francisco Aguilar (I).

According to Diccionario de la música Labor, p. 30, A singer named Francisco de Ajofrín was active in Toledo Cathedral in 1499. Perhaps this singer was the composer of the villancico Por serviros triste yo for three voices in the Cancionero Musical de Palacio (E-Mp II-1335).