A protocol of monitoring and treatment in toxoplasmosis is suggested by the authors. During pregnancy, the administration of spiramycine at a 9 m UI daily dose remains the basic preventive treatment when a seroconversion occurs after a 4 week post-conception period. In the fetus, the antenatal diagnosis is made by ultrasound started on the 18th week after conception and repeated every 4 weeks, amniocentesis and eventually umbilical cord puncture associated with a pyrimethamine-sulfamide drug treatment in case of positive diagnosis. A therapeutic pregnancy termination is considered when lesions have been detected by ultrasound. In the newborn (neonatal or post-natal period), the diagnosis is made by transfontanel ultrasonography, ocular fundi and spinal fluid examination, detection of specific IgM antibodies in cord blood and the evolution and importance of serum antibodies response requiring a drug treatment during 15-18 months with spiramycine and pyrimethamine + sulfadoxine (Fansidar).