In this paper, the population biology of the velvet belly lantern shark, Etmopterus spinax, was studied and life history parameters determined. Age was estimated from sections of the 2nd dorsal spine and validated by marginal increment analysis. Males attained a maximum age of 8 years while 11 year old females were found. Several growth models were fitted and compared for both size- and mass-at-age data, showing that even though this is a small sized species, it has a relatively slow growth rate. This species matures late, specifically at 49.6% and 42.5% of the maximum observed ages for males and females respectively. It has a low fecundity, with a mean ovarian fecundity of 9.94 oocytes and a mean uterine fecundity of 7.59 embryos per reproductive cycle. This species seems have a long reproductive cycle, and even though no conclusive data was obtained, a two to three year cycle is possible. The estimated parameters indicate that this species has a vulnerable life cycle, typical of deep water squalid sharks. Given the high fishing pressures that it is suffering in the NE Atlantic, this lanternshark may be already facing severe declines or in risk of facing them in the near future.