Following notification of suspected cases of diphtheria, investigation was carried out from 25th to 26th June, 2013 in the village of Tangoushmane. The objective was to conduct an analysis of the situation and support the health district in the preparations for response activities. Data were collected by an interview conducted at the village level and health workers and documentary and line list review. The analysis was done using Excel tables and pivot charts. The investigation revealed that all patients had consulted at the stage of false membranes and most of the deaths occurred at home or after hours or even days of observations the CSI seems to be the index case occurred April 23, 2013 in the village of Tezguene. The daily evolution showed intermittent occurrence of cases suggestive of spread from person to person. The case fatality rate was 39%, ranging from 10% to 58% to Tezguene Tanghousmane. The age of cases ranged from 3 years to 61 years (mean = 16.7 years) and the age range of 5-14 years is 63.4%.Particular attention should be paid to capacity building of staff in the definition of cases and routine vaccination in the district.