Primary hyperoxaluria type 1 (PH1) is an ultrarare, autosomal recessive metabolic disorder caused by mutations of the AGXT gene, encoding the liver specific peroxisomal enzyme, alanine:glyoxalate aminotransferase (AGT). It disturbs the glyoxalate metabolism and leads to hepatic overproduction of oxalate and its increased urinary excretion (hyperoxaluria). In majority of cases, first symptoms are observed during childhood as recurrent calcium- oxalate (CaOx) urolithiasis and/or nephrocalcinosis causing oxalate nephropathy, progressive chronic kidney disease (CKD) and end stage renal failure. Decreased renal clearance leads to oxalosis- systemic disease caused by multiorgan CaOx deposition. Until recently, the liver transplantation (LT) was the only causative therapy, performed usually parallel with the kidney transplantation in patients who reached CKD stage 4-5. Unfortunately, symptomatic treatment (hyperhydration, alkali citrate, low oxalate diet) as well as pyridoxine therapy are not satisfactory in majority of patients. The approval of lumasiran - the new orphan drug based on the RNA interference seems to be a breakthrough in PH1 treatment. It silences glycolate oxidase- the key enzyme of glyoxalate metabolism and therefore decreases hepatic oxalate synthesis. This innovative strategy gives a reasonable hope for an effective treatment and may replace the necessity of the LT in patients with PH1.