A discussion of cost estimation methods, prepared in connection with the estimating of costs of corrective measures, Ohio River Pollution Control Report, and based on inspection reports, for use with a lecture at the Public Health Service Training Course for Sanitary Engineers in Stream Pollution Abatement Programs, Environmental Health Center, Cincinnati, Ohio, 1949. Corrective measures and their costs, by type of industry, for the most common and most numerous industrial wastes in the Ohio River Basin are described.