The study shows the gasometric and electrolytic features during the first five day from newborns from toxemic mothers. It is a prospective study, carried out during a four month period at the obstetrics premature ward at the Gynecological-Obstetrics Hospital of "La Raza" Medical Center. Thirty-three newborn babies with evidences of toxemia and who had not received any intravenous therapy were studied. Blood samples were taken and serum calcium, phosphorus and magnesium levels were measured at 24, 48, 72 and 120 hours after birth. The results showed that six patients (18%) were anemic, and another had polycythemia. Twelve others (36%) had plaquetopenia, one had hypercalcemia, another hypocalcemia, and eleven (33%) presented hypophosphatemia. Of the initial 33 patients, 75% presented metabolic acidosis which spontaneously corrected itself within the following 72 hours. Three showed signs of hypernatremia, four hyponatremia, and two others hyperkalemia, with a return to normal levels within the next 24 hours. No chloride alterations were found in any of the patients. Some newborn babies born from toxemic mothers can spontaneously correct their electrolytic and acid-base imbalance within 72 hours of their birth. Electrolytes; toxemia.