Insulin promotes different biological effects through a coordinated signaling network in vertebrate cells. Many evidences suggest the presence of insulin-like peptides in plants. Some studies have reported insulin as growth-promoting factor in plants. Also insulin stimulates glyoxylate cycle enzyme activities in germinating sunflower, watermelon and cucumber. In maize cells, insulin induces activation of a signal transduction pathway, similar to its action in animals. The work reported here is an effort to understand the molecular mechanism through which insulin acts in plants. Seed coats, cotyledons, epicotyls and radicles of seeds with 72 h of imbibition in an insulin solution (0.9 mg) or in water (control seeds) were ground under liquid nitrogen. These tissue powders were extracted by 80 % ethanol and centrifuged. The starch was extracted from the pellet with 0.2 M KOH at 95°C for 60 minutes and neutralized with 1M acetic acid. A Sigma starch kit was used to measure starch levels. The tissues were also extracted with 100 mM HEPES-NaOH (pH 7.5), 5 mM MgCl₂ and 1mM dithiothreitol (DTT) for sucrose phosphate synthase and invertase activities measurements.  We had previously observed that insulin was responsible for raising the length of radicles and epicotyls, the masses of radicles and epicotyls as well as the number of lateral roots from Phaseolus vulgaris axes. The same was observed for an insulin mimicker, the pinitol. Insulin had also inhibited the ethylene production by germinating P. vulgaris seeds at 72 h and 96 h of imbibition and reduced the sucrose content of radicles (19%), epicotyls (40 %) and cotyledons (11 %). Here we observed that levels of starch have only been altered in radicles, where they decreased 54.25 % in seedlings treated with insulin. Acid invertase activity was only detected in radicles and epicotyls and this activity was not altered by the insulin treatment. The sucrose phosphate synthase activity decreased 59.5 % in the radicles treated with 0.9 mg/mL insulin when compared with control radicles. Altogether, the results suggest that insulin, in plants, may be involved in signaling pathways – however temporal and tissue regulation aspects may be finely involved with such effects.