Possible effect of fructose 2,6-bisphosphate over phosphofructokinase (PFK) and fructose 1,6-bisphosphatase (FBPase) has been measured on vegetative and differentiated phase cells of Dictyostelium discoideum. Partially purified PFK from D. discoideum was demonstrated to have Michaelian kinetics for its substrates fructose 6- phosphate and ATP (Km values: 22-23 uM and 6-7 uM for fructose 6-phosphate and ATP respectively). PFK has shown to be non sensitive to all known positive and negative effectors and to fructose 2,6-bisphosphate despite concentrations used, exceding l000-foldendogenous range. Partially purified FBPase from D. discoideum exhibited Michaelian kinetic regarding to fructose 1,6-bisphosphate, with Km: 1.2 uM. FBPase was inhibited by fructose 2,6-bisphosphate in nanomolar range (Ki: 1 uM), without synergistic effects with AMP. These results suggest that in Dictyostelium discoideum, fructose 2,6-bisphosphate could exert a regulator role in the gluconeogenic pathway but not in glycolitic one.