<p class="abstract"><strong>Background:</strong> Vitamins are very important for the human body because they are necessary for many biological absorption processes of other nutrients, for cells and tissues growth and repair. Because of this, there are many recommendations on daily vitamins intake, approved by the different country and world food organizations. Usually under the term "vitamin B<sub>12</sub>" is understood only cyanocobalamin, but actually this name is general and covers all potentially biologically active "cobalamins"- a group of cobalt-containing compounds. Animal foods, as different meat, milk, eggs, fish and shellfish are considered as the main dietary sources of this vitamin. They contain different forms (methylcobalamin and deoxyadenosylcobalamin) of vitamin B<sub>12</sub> in different amounts. There is limited information in the scientific literature about the vitamin B<sub>12</sub> content in black sea fish and shellfish. The aims of the present work were to determine and compare vitamin B<sub>12</sub> contents as well as relative daily intake of vitamins in different fish and shellfish species from Black Sea waters.</p><p class="abstract"><strong>Methods:</strong> Vitamin B<sub>12</sub> was analysed spectrophotometrically. The method for quantitative analysis includes extraction from the edible tissue and enzymatic hydrolysis to release the cobalt ions. </p><p class="abstract"><strong>Results:</strong> The quantities of vitamin B<sub>12</sub> found in the edible tissue of the analysed samples ranged from 0.63 μg.100 g<sup>-1</sup> ww to 21.5 μg.100 g<sup>-1</sup> ww.</p><p class="abstract"><strong>Conclusions:</strong> The observed results confirm that all fish and molluscs samples deliver significant quantities of the water-soluble vitamin B<sub>12</sub>.</p><p> </p>