PURPOSE:A detailed analysis in the iconography and pictorial appearance of the scene of the "Prophet Jonah" painted by the artist Michelangelo Buonarroti (1475-1564) on the ceiling of the Sistine Chapel between the years 1508 and 1512. MATERIALS AND METHODS:Literature review on the Italian Renaissance period and the life of Michelangelo Buonarroti and analysis of historical aspects of the evolution of studies of human anatomy in this period and the works of the artist. RESULTS:A comparative analysis of the representation of the figure of the fish on the left thigh of "Jonah" with a cross section of penis shows a curious similarity. The pictorial and iconographic analysis reveals an intensity of light on the pubic area and the position of the prophet with the legs spread apart and left hand placed on this region. A tube-shaped cloth covers the region and the angel at the side seems to be looking at this anatomical region of "Jonah". In fact, sets of iconographic and pictorial relate to the deciphered code. CONCLUSIONS: This description helps to confirm the relationship of the Renaissance art with the human anatomy; science has been much studied in this period. The design of a cross section of the penis is revealed with the two cavernous bodies with the septum between them and the spongy body. Considering the circumstances in which Michelangelo had painted, subjectivity was fundamental due to religious motivations added to the vigorous implications of a limited scientific knowledge typical of that era.