Privacy-preserving record linkage (PPRL) aims at integrating sensitive information from multiple disparate databases of different organizations. PPRL approaches are increasingly required in real-world application areas such as healthcare, national security, and business. Previous approaches have mostly focused on linking only two databases as well as the use of a dedicated linkage unit. Scaling PPRL to more databases (multi-party PPRL) is an open challenge since privacy threats as well as the computation and communication costs for record linkage increase significantly with the number of databases. We thus propose the use of a new encoding method of sensitive data based on Counting Bloom Filters (CBF) to improve privacy for multi-party PPRL. We also investigate optimizations to reduce communication and computation costs for CBF-based multi-party PPRL with and without the use of a dedicated linkage unit. Empirical evaluations conducted with real datasets show the viability of the proposed approaches and demonstrate their scalability, linkage quality, and privacy protection. 4 b (n / b ) 4 b (n / b) b (n / b) b (n / b) b (n / b) Linkage Unit (LU) Candidate record sets Candidate record sets Linkage Unit (LU) b (n / b) 2 3 4 4 4 b (n / b ) b (n / b ) 4 b (n / b ) 3 b (n / b ) 2 Figure 1: An overview of traditional naïve comparison of candidate record sets masked using BFs (left) and CBFs (right, as will be described in detail in Section 3) from p = 4 parties using a LU . Databases are indexed/blocked to reduce the number of candidate record sets such that only records in the same blocks are compared and classified. Blocks are illustrated by different patterns in D i , with 1 ≤ i ≤ p. n denotes the number of records in the databases (assuming all databases are of equal size) and b denotes the number of blocks generated (assuming blocks of equal size). Independent of the masking function and the communication pattern used (i.e. BFs and direct one-to-one communication in the left figure, and CBFs and ring-based communication in the right figure), the naïve approach results in exponential complexity of b (n 4 /b 4 ) candidate sets each consisting of p = 4 records (one from each party).Contributions: Our contributions in this paper are: (1) a novel multi-party PPRL protocol based on CBFs and secure summation for efficient, approximate, and private linkage; (2) two variations of extended secure summation protocols for improved privacy against collusion among the data base owners: (a) homomorphic encryption-based and (b) salting-based (using random seed integers); (3) two efficient