Many CRORS members are also members of other relevant societies, academic institutions and seminars in Croatia with whom CRORS has a good collaboration. Their activities and lectures organized in the field of operations research:

Seminar for Theory of Computation
Department of Mathematics, Faculty of Science, University of Zagreb
Seminar for Theory of Computation is organized within the post-graduate studies at the Department of Mathematics, Faculty of Science of the University of Zagreb. The seminar has been very active, counting around 18 lectures since October 2017..

Seminar for mathematical programming and game theory
Department of Mathematics, Faculty of Science, University of Zagreb
The Seminar for Programming and Theory of Games was established within the Institute of Mathematics, University of Zagreb in 1966, with the aim of intensifying scientific work in the field of practical mathematics. The Seminar brings together scientist and topics in mathematical programming and game theory, their applications in mathematics, statistics, mathematical economics, but also practical applications in various fields of business and economics.

HMD Engineering Section Seminars
Croatian Mathematical Society
The Engineering section of HMD mainly consists of mathematicians working in economic practice (but not only them), who apply OR methods in their work, and who participate in the KOI conference. The majority of CRORS members are on the mailing list of the engineering section of HMD and actively participates in its seminars.

Mathematical Colloquium
Department of Mathematics, University of Osijek
Mathematical Colloquium in Osijek is active since 1993, as an activity of the Scientific Section of the Osijek division of the Croatian Mathematical Society and the Institute for Applied Mathematics in Osijek with the help of the Central branch of the Society in Zagreb and the Department of Mathematics, University of Zagreb. Since 1999, Mathematical Colloquium has been organized by the Department of Mathematics, University of Osijek. Lecturers of the scientific colloquium are researchers from Croatian universities and abroad who usually report on their researches, Ph.D. theses, or give an overview of recent trends in mathematics and its applications. They usually present their ideas and approaches to teaching or discuss a historical topic connected to mathematics and mathematicians.

Optimization and Application Seminar
Department of Mathematics, University of Osijek
Organized by the Department of Mathematics, University of Osijek, the Optimization and Application seminar covers topics such as mathematical modeling, problems of identification and estimation of parameters in mathematical models, statistical aspects of the problem of identification and estimation of parameters in mathematical models, optimization of mechanical systems, applications in natural, technical and other sciences. Basic seminar outline is a presentation of original papers, presentation of papers from literature and guest lectures.