A Double Blinded Privacy-Safe Distributed Data Mining Protocol is disclosed, among an aggregator, a data consumer entity having privacy-sensitive information, and data source entities having privacy-sensitive information. The aggregator does not have access to the privacy-sensitive information at either the data consumer entity or the data source entities. The aggregator formulates a query without using privacy-sensitive information, and sends the query to the data consumer entity. The data consumer entity generates a list of specific instances that meet the conditions of the query and sends the list, encrypted, to the data source entities either directly or through the aggregator. The data source entities match the list against transactional data, de-identify the matched results, and send them to the aggregator. The aggregator combines results from data source entities and sends the combined result to the data consumer entity. This allows for privacy-safe data mining where both the data consumer entity and data source entities have privacy-sensitive information not available for the aggregator to see or use.