/* sort the two datasets by a common variable that has  	*/
/* a unique value for each case.				*/

proc sort data=dataset1;

  by id;

proc sort data=dataset2;

  by id;

/* combine the two datasets.  it does not matter if there is	*/
/* missing data or an unequal number of cases			*/ 

data newdata;

  merge dataset1 dataset2;

  by id;

run;