1. International collaboration in freshwater ecology was examined using authorship affiliations of articles published in thirty‐three specialized journals. Most are published in Europe.
2. Researchers from four to thirty‐seven different countries were represented in the 100 articles examined for each journal. Only 29% of articles were single‐authored; multicountry authors' addresses (indicating international collaboration) were found for 9% (range 0–23% per journal) of articles examined.
3. Five of the eighty‐nine countries listed in the addresses of the 3300 articles together contributed >50% of total articles: United States (24.9%), Canada (8.6%), Germany (7.6%), Commonwealth of Independent States (7.0%) and Poland (5.9%). Of the fifteen countries that each produced >2.5% of total articles, the percentage representing international collaboration was highest for France (34.9%) and Canada (24.0%). The seventy‐four countries that each contributed <2.5% of total articles generally had higher rates of international collaboration.
4. Researchers in the United States and Canada collaborate internationally almost twice as often in freshwater ecology than in all science. Much of France's extensive international collaboration is with countries that produce few articles in freshwater ecology, and their international collaboration is often exclusively with France.
5. Three journals publishing both marine and freshwater ecology articles contain more articles on the former topic, but more countries are represented in the publication of freshwater than marine research.
6. The percentage of articles that represent international collaboration is higher in freshwater ecology than in medicine, biology, chemistry and engineering, and approximates that in physics.
