We show by means of Monte Carlo simulations that a stretched exponential probability density function suggested recently in a single-enzyme study of CALB is not consistent with the experimental distribution of off-state waiting times. The cause of the inconsistency is that the experimental resolution was too poor to support a stretched exponential with a fast characteristic time scale. We believe, that the question as to statistical interpretation of single-enzyme kinetics of CALB remains open. (c) 2006 Elsevier B.V. All rights reserved.