> Format your dataframe into a long format. Then use a grouping variable > to distinguish both lines. > > library(ggplot2) > DF <- data.frame(X = rep(0:20, 2), Y = c(rnorm(21), runif(21)), Z = > gl(2, 21)) > ggplot(data = DF, aes(x = X, y = Y, colour = Z)) + geom_line() You can also use ggplot and then add layers for each geom_line that you want to add. Vikas >