Since 2005 up to 2006 diphtheria out break had occur in Tasimalaya District among 1 – 15 year old children. Total cases are 55 children with cases died with the Case Fatality Rate (CFR) 31.91%. Further on, January 2007 the same out break occur in Garut District, with 17 cases and 2 cases died (CFR 11.76%). Research objective is to identify the correlation of housing environmental condition with the diphtheria out break. Design study was case control study. The amount of 72 cases had taken from the 15 villages on the out break areas and the same amount (72) non cases taken from the village out of the out break areas. Data were collected through interviewed with structure questioner with the mother as the respondent. Data collected were housing environment, the source of infection, immunization status, and mother knowledge concerning the diphtheria. Research conclude that factors involved in diphtheria out break are housing member room density, housing humidity, quality of the floor, the source of the infection, immunization status of the children, and mother knowledge about the disease. The importance factors for the diphtheria out break are immunization status, with the OR of 46.403 greater of non immunization children compare with those had immunization. Therefore immunization program should be further intensified in order to give fully diphtheria protection for the hole children population in those areas.