I'm running tomcat under FreeBSD jsmith.org 5.1-RELEASE-p10 FreeBSD 5.1-RELEASE-p10 #0: Wed Oct 8 10:46:17 EDT 2003 root at jsmith.org:/usr/obj/usr/src/sys/GENERIC i386 and JDK 1.4.1 without any problems. I'm not using the Tomcat port, though --- I'm using a version of Tomcat I compiled from source under Linux.