This essay proposes an addition to the catalogue of Bartolomeo Manfredi through the presentation of a previously unpublished 'Penitent Saint Jerome', identified from a photograph preserved in the Zeri Photo Archive. The work, securely attributed to the Caravaggesque master, can be dated to his mature period, between 1620 and 1622. The painting introduces a rare iconographic variant: the saint is depicted as a half-length figure engaged in eremitic penance, striking his chest with a stone, in contrast to the more common representation of Saint Jerome writing. The figure displays marked physiognomic and stylistic affinities with the 'Saint Jerome' in Palazzo Barberini in Rome, which is here, in turn, proposed for redating to the artist's final years.