The paper aims at assessing the research output of scientists working in “hard sciences” at six Croatian Univeristies (Dubrovnik, Osijek, Rijeka, Split, Zadar and Zagreb). The data obtained may serve as the starting point for further follow-up and in-depth studies of research performance at Croatian universities. This can be particularly relevant for implementation of the Bologna Process in Croatia. The methodology of the Academic Ranking of World Universities (2004) was applied (http://ed.sjtu.edu.cn/rank/2004/Methodology.htm). The number of papers published from 1996 to 2004, registered in the WoS-Science Citation Index-Expanded, authored by scientists from the six Croatian universities, was enumerated. Also, highly cited authors, authors of articles published in Nature and Science, Nobel Prize and Fields Medal winners were sought among these scientists. It was found that scientists at the Croatian universities produced 7527 of the total of 11 068 articles authored by Croatian scientists. Of the six universities, the University of Zagreb was more productive than the remaining five. There were no highly cited authors, Nobel Laureates or Fields Medal winners from Croatia. One of 14 authors of an article in Science was from a Croatian university. Also, a letter on science policy, appearing in Nature, had one of two authors from Croatia. It can be concluded that scientists performing research in “hard sciences” at six universities in Croatia contributed about 68 % of all the articles published by Croatian scientists. University of Zagreb was the most productive.