He died young from a fever he contracted while attending a patient in the neighbourhood of Tuam.
His death occasioned a lament titled Doctúir Jennings, composed by Patrick Greaney.
Is tú fuair bás uainn i dtús do shaoghail: Dá siubhalainn Connacht agus Oileán Phádraic Samhail mo mhaighistir ní bhfuighinn i dtír Nuair a bhreathnuighim síos ar Pholl an Iarrain, Cé an cás dom bliadhain acht arís go deó, Ins an áit a h'oileadh an leannaibh uasal.
Acht nach truaigh sin a's mo chreach, é'r lár!
This biographical article related to medicine in Ireland is a stub.