The emerging field of metabolomics, in which a large number of smallmolecule metabolites are detected quantitatively in a single step, promises immense potential for early-diagnosis, monitoring, and understanding the pathogenesis of many diseases. The clinical/ biochemical findings in some inborn errors of metabolism (IEM) are often nonspecific; an early differential diagnosis made in a single urinary sample it gives an important advantage. We present the spectrum of uriny metabolites from a 1 year-old girl with stroke-like episode, elevated transaminases, coagulopathy, being first interpreted as encephalitis. Beside the clinical presentation, the fast results gave by urinary NMR-spectrum showing a high concentration of orotic acid indicates the OTCD diagnosis. Beside this, we present our results and the utility of this method for rapid diagnosis and monitoring steps for galactosemia and alkaptonuria. The level of excretion of the metabolites in these three IEM has been well within the range of NMR detection. In the critical care setting, IEM that were not diagnosed through the neonatal screening should be considered as cause of acute neurologic, hepatic/ renal decline, rapid diagnosis being essential. We demonstrate the effective use of NMR-spectroscopic-profiles of urine in differential diagnosis for UCD and the possibility of management in other IEM. Background: Autism or autism spectrum disorder is a quite common neurodevelopmental disorder presenting in childhood. Although genetic factors play an important role in the etiology of autism, environmental toxicities, such as metal or xenobiotic toxicity are also important factors in this disorder among some of these children. The aim of this study is to examine the relationship between urinary porphyrins, biomarkers of oxidative stress and heavy metals in Turkish autistic children. Material and Methods: Urinary porphyrins were measured by an HPLC method; malondialdehide, arylesterase were assessed by colorimetric methods. Also, Pb, As, Cd, Hg were measured by AAS methods in the first morning urine samples of 36 autistic children and 26 age-matched control subjects. Results: Compared to the control group while there was no difference in the other urine parameters, urine total coproporphyrin and coproporphyrin-III levels were increased statistically significant (p<0.05) in autistic children (Patient group; copro-III:109.2 ±62.7, total copro: 176.5 ±146.9; and control group; copro-III:41.5 ±11.9, total copro:72.7 ±17.0 nmol/L respectively). There was no significant correlation between urinary porphyrin levels in urine and other parameters. Conclusion: Increased levels of urinary coproporphyrin may reflect the effect of environmental toxicity in Turkish autistic children Recessive hereditary methemoglobinemia (RHM) type 2 is an autosomal recessive metabolic disorder due to generalized deficiency of cytochrome b5 reductase (cytb5r). In contrast to RHM type 1, an almost benign disorder where cytb5r-deficiency is restricted to erythrocytes, a severe clinical picture with microcephaly, psychomotor retardation and dystonia develops. Cyanosis may be mild with methemoglobinemia values ranging between 10-42%. We hereby present a female patient, cyanosis noted immediately after birth, showing elevated methemoglobin values (8-19%). Erythrocyte cytb5r-activity was severely reduced leading to diagnosis of congenital methemoglobinemia. Excessive crying was observed from the sixth week of life, followed by vomiting and dystrophy. In the twelfth week of life deceleration of head growth, neurological impairment with no fixation and smiling, poor head control and opisthotonous were noted. Fibroblast cytb5r-activity was markedly reduced proving RHM type 2. Two novel mutations in the CYB5R3 gene were detected (maternal point mutation and paternal deletion) resulting in a premature stop codon. At 2,5 years the patient shows severe psychomotor retardation and mean methemoglobin values of 12%. Unexplained lactate elevation occurred intermittently. Medication with ascorbic acid, riboflavin and toluidine blue had no clear clinical benefit. We hereby draw attention to this rare disorder which is probably underdiagnosed.