The methods used in obtaining polyploid cassava (Manihot utilissima Pohl) by colchicine treatment were described in detail. Two solutions of colchicine were tried, one at 0.5% and other at 1.0%, both giving identical results in producing many altered plants. The chromosome number of the altered plants was determined and [a correlation between chromosome duplication and increase of the major diameter of stomata was found. Size of stomata in cassava serves to identify poliploids individuals if the plant produced by treatment is not a chimera, a very frequent event in producing polyploid cassava by colchicine. It was emphasized that the plants obtained by treatment were a type of chimera, with the aerial part polyploid and the subterranean base diploid. The development of polyploid individuals obtained from the polyploid aerial part of the treated was analyzed. A comparison between the tetraploid and the diploid control plants was made, the octoploid plant being too slow in development. There are many groups of polivalents in the first meiotic metaphase of the autopoly-ploid individuals obtained. By an analysis of the polen grains it was assumed that the diploid plant may be a structural hybrid. The production of the tetraploid plants was computed preliminarly, other detailed experiments involving spacing being necessary for estimating the commercial production,, since the diploid produces more branched plants than the tetraploid ones.