A rare case of pregnancy in a patient with primary hyperoxaluria type 1 is reported offering a clinical contribution for the prognostic study of a natural event such as the pregnancy on these patients. It is underlined how epicriticity of the hepatorenal system is remarkably altered during the last weeks of pregnancy with a great increase of calciuria and proteinuria with a risk of life for the patient and the newborn. In fact, during the 36rd week a caesarean section was performed due to gestosis. Moreover, the deterioration of kidney functionality doesn't decrease during post partum. Therefore, it would be advisable inform these patients about the risk of pregnancy.