Hello, I have aggregate a data.frame from 16MB (Object size). After some minutes I get the error message "cannot allocate vector of size 64.5MB". My computer has a physical memory of 4GB under Windows Vista. I have test the same command on another computer with the same OS and 2GB RAM. In nearly 2sec I get the result without problems. Thanks buch<-read.delim("Y2006_1.csv",sep=";",as.is=TRUE,header=TRUE,dec=",") ana01<-aggregate(buch[,c("VALUELW","LZLW","SZLW")],by=data.frame(buch$PRODGRP,buch$LAND1,buch$KUNDE1),sum)