Abstract
1. A consecutive series of 400 cases of diphtheria from the Romford (Essex) area have been bacteriologically typed and correlated with the clinical findings.2. Gravis infection was found to be the most prevalent type.3. The intermedius type was the most lethal and severe.4. Mitis infection formed the smallest proportion of cases, usually of a mild character.5. Laryngeal cases were few, and all three bacteriological types were represented.6. A large proportion of children of 7 years and over were attacked.