Microbiology General d8484cdd Incubation period of Diptheria is - A 2 - 6 days B 2 - 6 hrs C 2 - 6 weeks D 2 - 6 months High-Yield Explanation . Ans. is `a' i.e., 2 - 6 days - The incubation period of diphtheria is commonly 3-4 days.