Syphilis during pregnancy has a high risk of transmission from mother to fetus and penicillin is the only validated treatment to avoid fetal and neonatal consequences. A healthy female 33 years old was diagnosed with syphilis at the first trimester of pregnancy and treated with oral erythromycin because penicillin allergy. VDRL titer increase from 1:2 to 1:4 after treatment and she was treated with the same compound again. Two obstetric ultrasounds did not show abnormalities at 22 and 31 weeks of pregnancy. The patient was admitted at 36 weeks with labor symptoms and the VDRL titer this time increase to 1:8 and fetal hydrops was demonstrated by ultrasound. A desensitization penicillin protocol was applied without complications and intramuscular benzathine G penicillin was indicated afterward. She gave birth to a preterm newborn with early congenital syphilis characterized by anemia, thrombocytopenia, leukocitosis, pleural effusion, scites, pneumonia alba, respiratory failure, hepatomegaly and vesiculobullous skin lesions involving palm and soles. In addition, placental hystopathological analysis demonstrated necrotizing funisitis. The newborn improved progressively with supportive care at the neonatal ICU unit and intravenous sodium penicillin G and was discharged alive. Her VDRL titer was 1:16. In contrast to international guidelines that advocate for penicillin desensitization in pregnant mother with syphilis, the Chilean normative indicates erythromycin therapy despite its known therapeutic failure. As this case illustrate, the Chilean normative on the management of pregnant women with syphilis and penicillin allergy should be revised and modified to avoid congenital syphilisDear Editor, Syphilis during pregnancy has a high risk of transmission from mother to fetus, especially during early phases of infection. Consequences are disastrous and include abortion, stillborn, premature birth, intrauterine growth retardation, perinatal death, and congenital syphilis. (1) Penicillin remains the drug of choice and is the only validated therapeutic option for maternal syphilis. Treatment failures are of rare occurrence and may be explained by reinfection, HIV infection, incomplete doses, or placental insufficiency impeding drug delivery to the fetus. Pregnant women allergic to penicillin impose a therapeutic challenge due to reported failures to prevent congenital infection after macrolide treatment either by a low transplacental passage of the antibiotic compound or antibiotic resistance. (2,3) Alternatives such as doxycycline and tetracycline are contraindicated. Due to the great dependence on penicillin to achieve a therapeutic success in the fetus, guidelines from the CDC and other countries advocate for penicillin desensitization every time is possible. (4) Contrary to this recommendation, the Chilean normative does not consider desensitization as an option and impose erythromycin treatment. (5) Unfortunately, this option was published as a rule and not as a guideline. Read more....