Childhood diseases are an inexhaustible topic and great interest in all areas of both general and dental medicine. Congenital, developmental and hereditary diseases may be present at birth, or occur in early childhood age. Infectious diseases are relatively common in the children's population because of the constant exposure of children to microorganisms. According to agents, infectious diseases can be divided into bacterial, viral and fungal infections. Bacterial infections can be odontogenic and non-odontogenic. The most common bacteria present in children are streptococci and staphylococci. The most common cause of fungal infections is C.albicans. Clinically, there are different types of candidiasis, and in children, most common are pseudomembranous and erythematous forms and cheilitis angularis. Viral infections can be grouped according to the genetic material of a virus: DNA or RNA. Viral infections can also be divided into primary, if they only affect the oral cavity, and secondary, if the whole organism is affected. Herpes simplex type one infection may occur as herpetic gingivostomatitis or herpes simplex recidivans. Coxsackie virus in children can cause herpangina or hand, foot and mouth disease. Children with HIV infection are often infected during pregnancy from infected mothers. Other sources of infection in the pediatric population are blood products, transfusions and breastmilk. Benign tumors and various types of oral mucosal injuries are also relatively common in childhood