I've been using iReport 4.0 where I could find a way to add my custom jars. Using the actual v5.6.0 of Jasperstudio is killing me. Like drummer54, I can't find a way to have them taken into account while designing. Any help would greatly be appreciated. Thanks in advance, EDIT: After sooo much efforts to get something to work, I found out that referencing external class path with .class file may work. Though you may consider refreshing project/files to have new modification taken into account. To me it seems that classpath is not taken into account as immediatly as in a standard Java project. Hope this can help