Infection transmission in dentistry is an inevitable issue that occur variously, and one of the contamination transmission ways is dentist’s mobile phone. Therefore, this study has been performed aiming at “Investigating the Ratio and Type of Bacterial Contamination of Dentists’ Mobile Phones in Dentistry Unit of Sina Hospital in Ahvaz in 2014”. In this cross-sectional, analytical, and descriptive study, sampling was performed from mobile phones of 77 dentist of the city of Ahvaz and 10 normal citizens by using moist sterile swab impregnated by normal saline. Then these samples were transmitted to the laboratory and were cultured in blood agar culture medium at 37 ° C for 24 hours, and based on bacterial colony ratio, the existence of contamination and its type was specified. The ratio of bacterial contamination of the mobile phones of dentists and normal citizens was 100 percent. In respect of the number of bacteria type in most cases, that is 55.8 percent, the number of bacteria types identified on the dentists’ mobile phone has been one type. In respect of bacteria type, Bacillus SPP existed in 23.4 percent, and Coagulasenegative staphylococci existed in 11.7 percent of dentists’ mobile phones. The relationship between the type and number of bacteria observed on the mobile phones with the gender, age, the status of dentist’s specialty was not statistically significant (P>0.05). Offering solutions in order to minimize the use of mobile phones and regular disinfecting mobile phones in the clinical environments are recommended.