Background and objective: The thalassemias are a diverse group of genetic blood diseases characterized by absent or decreased production of globin chains. Clinical studies about b-thalassemia major patients, has shown an increase in prevalence of dental caries. The purpose of this study was to determine oral health and biochemical status of saliva in thalassemia major patients.Methods: Thirty one thalassemia patients and 31 healthy persons who were the same according to age, sex, socio-economic status and exposure to fluoride, were examined for dental caries (DMFT) and oral hygiene conditions (OHI-s). Two ml of unstimulated saliva was collected from each subject and the biochemical compositions (calcium, phosphorous, potassium, sodium, magnesium, urea, total protein) were measured.Findings: The mean of DMFT in thalassemia patients (5.26±4.16) was higher than control group (2.65±1.91) (p=0.003). In thalassemia patients, the calcium concentration (4.38±1.25) was lower than control group (5.23±1.18), but the phosphorus concentration (19.15±5.87) was higher than the control group (15.73+5.24) (p<0.05). There were no statistically significant differences in the mean of OHI-s and concentrations of sodium, potassium, magnesium, urea and total protein between two groups.Conclusion: changes in ions concentrations can be a result of more dental caries in these patients.