Lysinuric protein intolerance (LPI) is a rare inherited metabolic disease. It is caused by a deficiency in cationic amino acid transport caused by mutations in SLC7A7 gene. To identify the clinical, diagnostic and therapeutic features of lysnuric protein intolerance. This was a retrospective study conducted in the pediatric department of La Rabta Hospital over a period of 30 years (1992 to 2022). We included patients with clinical signs suggestive of lysinuric protein intolerance and orotic acid in the urine. We enrolled seven patients. The median age at disease onset was nine months. The median age at positive diagnosis was 21 months. Growth retardation, hepatosplenomegaly and haematological abnormalities were the main features of the disease. Hyperammonia and increased urinary orotic acid were present in all patients. Molecular biology revealed the del TTCT 1471 mutation in five patients. All patients were prescribed a low protein diet and citrulline supplementation. Complications of the disease were growth retardation (n=7), psychomotor or intellectual retardation (n=5), haemophagocytic lymphohistiocytosis (n=4) and osteoporosis (n=3). After a median follow-up of 11 years, six of our patients are still alive. One patient died from acute hyperammonemic encephalopathy. In this paediatric series, delays in diagnosis and treatment of LPI were responsible for long-term sequelae, particularly bone and neurological. The delTTCT1471 mutation appears to be the mutation of paediatric-onset forms in Tunisia. This mutation was not associated with pulmonary involvement, which is a prognostic factor and the main cause of death.