Escherichia coli cells lose viability when irradiated with visible light in the presence of acridine dyes. There has been some controversy about whether such photodynamic damage can be repaired. Several investigations on different E. coli strains failed to reveal any significant difference in the sensitivity to photodynamic damage between radiation‐resistant E. coli B/r and radiation‐sensitive E. coli Bs‐1 strains (Uretz, 1964; Janovska et al., 1970) suggesting the absence of repair. On the contrary, other investigators (Rupp, 1966; Harm, 1968) strongly predicted the existence of a dark‐repair mechanism for such damage. No systematic study of liquid‐holding recovery of photodynamic damage has yet been reported and knowledge of repair capacity for photodynamic damage is still incomplete. In the present communication, liquid‐holding‐repair capability of E. coli B/r and Bs‐1 for photodynamic inactivation in the presence of acridine orange or acriflavine has been investigated. These studies show that B/r can repair photodynamic damage while Bs‐1 is deficient in this ability. Copyright © 1974, Wiley Blackwell. All rights reserved