In the present article the results of the genetical analysis of the characters of the maragogipe variety of Coffea arabica L are presented. This variety which originated as a mutation from C. arabica L. var. typica Cramer, in 1870, in the State of Baía in North Brazil, represents a gigas form of that variety, having larger leaves, flowers and fruits, its plants being also taller; it is also known for its low productivity. Since 1933 a genetical analysis of this variety was undertaken, many of its plants being selfed and crossed with other maragogipe plants and also with individuals of the typica and bourbon varieties of C. arabica; two generations have been studied, including F2's and several back-crosses. It was concluded that this gigas form is controled by one pair of almost completely dominant genes, for which the symbols Mg-Mg are proposed. The heterozygote (Mg-mg) is practically indistinguishable from the dominarit homozygote in all morphological characters; its productivity, however, seems to be a little higher than that of the homozygote.