Objectives: The aim of this study was to determine the type of Streptococcus pneumoniae which is more prevalent in different diseases. Method: 115 Clinical isolates of Streptococcus pneumoniae were re – identified and serotyped with Quellung test as a one of the serotyping methods based on SSI protocol - Statens Serum Institute. The data were inserted in to the computer and analyzed by SPSS version 17.0. Results: The results of this study showed that 41% of isolate belongs to Respiratory Tract Infections. It was also known that 22% of isolate belongs to blood infection and 26% to eye infections. Finally 11% of isolates belongs to other infection in the patient too. The findings of this study showed that the types of 6A and 6B are more prevalent in patients totally. In addition, this study indicated that the type of 2 is more prevalent in adult patients. Conclusion: This research revealed that types of 19F, 19A, 19B and 19C are more prevalent in Infant patients. This study also indicated that the most predominant types are in respiratory tract infections (group 7*), eye infection (group 19*), blood infection (type 5, 3, 6 and 4) and in CFS (type20) respectively. The diseases could be prevented by using the Pneumococcal vaccine.