The age, growth and fecundity of the Turkish Brook Lamprey, Eudontomyzon lanceolata (Kux & Steiner, 1972), was studied at Iyidere stream in the Black Sea region of Turkey. The total length values varied between 2.0 and 17.3 cm (average 11.38 cm), and the total weight values between 0.02 and 9.4 g (average 2.57 g). The sex ratio (female:male) was 1:1.16. Larvae start their metamorphosis after they reach 2 years, and metamorphosis extends over 3 years. It begins at the end of summer. Metamorphosis was observed in individuals longer than 13 ern, but even some larger individuals showed larval characteristics. Females in 4(th) year sampled between March and May had ovaries full of eggs. The absolute fecundity was found to be on average 1898.5 eggs/female. No individuals who had already laid eggs were found.