Background and objective:Nursing caries is a complex and severe form of tooth decay that affects a child's teeth and leads to severe pain, teeth loss, and psychological problems. This type of decay is caused by primary factors (host, cariogenic bacteria, fermentable carbohydrate and the time) and other secondary factors. Besides, the dental caries influence by the role of saliva as a defense system. These defense systems include clearance, buffering, antimicrobial agents, and calcium and phosphate delivery for remineralization. This study aimed to find out the relationship between calcium, inorganic phosphorus and alkaline phosphatase of unstimulated saliva in children with nursing caries. Methods:The sample included 374 children aged 4-6 years; 324 were the study group (with nursing caries) while 50 were control group (caries-free). The case sheet and questionnaire included the child's feeding habits and oral hygiene. A 1.5-2 ml of saliva was collected from the selected children using spitting technique. The method included dental examination for the recording of the dmft and dmfs indices, and saliva analysis to determine the level of salivary calcium, phosphorus and alkaline phosphatase in control and study groups. Results:The study group children demonstrated a statistically highly significant (P ≤0.01) higher saliva calcium (5.229 ± 0.963 mg/dl) and alkaline phosphatase concentrations (6.321 ± 1.792 KAU/dl) than the control group (4.968± 0.757mg/dl, 5.384 ± 2.119 KAU/dl), respectively. The same group demonstrated a statistically highly significant (P ≤0.01) lower inorganic phosphorus concentration (10.991 ± 1.376 mg/dl) than the control group (11.961 ± 1.484 mg/dl). The study group showed a lower percentage of breastfeeding (28.4%) in comparison to the control group (42.0%). Concerning mix-feeding, the study group showed the higher percentage (45.4%) in comparison to the control group (32.0%). The bottle-fed found to be equal in both groups, there was a statistically non-significant difference between the study and control group. Conclusion: Salivary calcium and alkaline phosphatase level have a major role in causing nursing caries in children. On the other hand, salivary inorganic phosphorus level showed a negative correlation with caries activity (dmfs). The type of infant feeding has no effect on the children with nursing caries. Keywords: Saliva; Nursing caries; Calcium; Alkaline phosphatase; dmft; dmfs. The early loss of deciduous teeth may create functional and esthetic problems and may lead to the loss in arch length that may interfere with the proper alignment of the permanent teeth. Therefore, preventive measures should be directed to retain primary teeth until their normal shedding time. 4 Iraqi studies were present regarding the correlation between salivary calcium, phosphate and alkaline phosphatase with dental caries.5 While no previous study about this subject had been done in Erbil city, therefore, this study was carried out as an attempt to determine the relation of calcium, phosphorus and al...