The Mediterranean monk seal Monachus monachus is the most endangered pin-niped in the world and is considered Endangered by the IUCN. Transition from suckling to active feeding is a critical time in the development of all mammal species, and understanding the dietary requirements of seals during this vulnerable period is of value in establishing conservation measures, such as fishery regulations. This study provides unique information on the dietary habits of a moulted monk seal pup, through the opportunistic necropsy of a dead animal encountered at a very early age (5 mo). A total of 6 prey items from 2 families (Octopodidae, 90.8% and Congridae, 8.9%) were identified from stomach contents. The remaining stomach content mass consisted of fish bones from unidentified species (0.3%). The estimated age, low diversity and number of prey items in the stomach contents indicate that this individual may have been in a transition period from suckling to active feeding. The study confirms independent foraging in Mediterranean monk seals at about 5 mo of age. Given the importance of early life survival for maintaining stable Mediterranean monk seal populations, and the occurrence of an ontogenetic shift in its close relative (Hawaiian monk seal), these findings contribute to the establishment and implementation of successful conservation and management strategies for this Endangered species.