We recently posted randomForestSRC on CRAN. It uses OpenMP in the native code extensively. We set the default number of cores to two (2), but we typically run it at the maximum (omp_get_max_threads()) during analysis. Currently, users need to set options(), set an environment variable, or edit their .Rprofile to use more than two cores. We followed the protocol for mc.cores in mclapply() in the package parallel. R CMD CHECK aside, is it acceptable to set the default to the maximum or is this not recommended? ubk -- kogalurshear at gmail.com (preferred) udaya at kogalur-shear.com Phone: 919-824-9825 Fax: 919-890-3868 Website: www.kogalur-shear.com Udaya B. Kogalur, Ph.D. Adjunct Staff, Dept of Quantitative Health Sciences, Cleveland Clinic Foundation Consultant, Kogalur Shear Corporation 6887 Idols Road, Suite B Clemmons, NC 27012