The author suggests a tecnique for the determination of vitamin A on shark liver oils in industrial plants. The advantages of using oly four ml. of reagent and of permitting a quickly rigorous reading by photoeletric cell, contribute to the possibility of the examination of a great number of samples daily; 2. It is described a survey on the vitamin A content of oils from shark livers, which has been made at the Finishing School Darcy Vargas, Marammaia Is., Rio de Janeiro State. The conclusions are the following: a) Male individuals have showed generally tendency for higher vitamin A pontency oils; b) The size of the fish does not interfere in the vitamin content of the oil (graphic 4); c) The data collected upon 3.085 individuals led to the conclusion that some species are richer in the reservated vitamin although it was possible to catch in the same specie fishes with widely variable potency in vitamin A. One fish belonging to the specie C. lamia produced the highest vitamin potency oil with 167.712 international units per gram; d) The fishing season appears to have no influence on the oils; e) The adventitous food seems to be the most important factor affecting the content of vitamin A of the shark-liver oils; 3. The presence and the quantity of vitamin D in those oils was investigated and two of the determinations are presented.