Here an example from http://stackoverflow.com/questions/16267440/grouping-boxplot-matlab. The example is about on how to create a boxplot for multiple group of variables. The example as follows:

x=rand(1000,6); %variable x y=rand(1000,6); %variable y D(:,1:2:12)=x; %rearrange x into d. D(:,2:2:12)=y; %rearrange y into d % first column of D, will fill with column of x, then second... % column of D will fill with 1st column of y. then the sequent... % will follow.

and

figure('color',[1,1,1]); %create a blank graph boxplot(D,'factorgap',10,'color','rk') %make a box plot on those blank graph axis([0 25 -1 5]) %not compulsory:rearrange back axis set(gca,'xtick',1.8:4.3:50) %put xtick to x-axis set(gca,'ytick',0:10) %put tick to y-axis set(gca,'xticklabel',{'Direct care','Housekeeping','Mealtimes','Medication','Miscellaneous','Personal care'}) %label to each x-axis ylabel('Normalised Y'); legend(findobj(gca,'Tag','Box'),'HBN04-01 multibed','YAB single ') %put legend to figure