Hi there, It has been some time trying to install and configure Rgraphviz to work with graphviz. here is a receipe which works quiet well install R from Darwin ports "http://darwinports.opendarwin.org/getdp/" by >sudo port install r this will take some time and installation of R will be done in /opt directory created by darwinports during its installation. as its not set in the environment variable by darwinports so set it in your .bash_profile or .tcsh files e.g export PATH=/opt/local/bin:$PATH also install other packages which are required for Rgraphviz like "graphviz" and "pkgconfig" by >sudo port install graphviz wait for a while >sudo port install pkgconig both these commands will also install dependencies which are required. After this Start up an R session being root and get the latest version of bioconductor packages by sourcing it from bioconductor website >source("http://www.bioconductor.org/biocLite.R") >biocLite() wait for a while and then install >biocLite("Rgraphviz",depend=TRUE,type="source") works fine, Anand Gavai Phd Student(Bayesian Networks) Laboratory of Bioinformatics, Wageningen University, Wageningen. The Netherland.