Hi There,   I recently came across the HASH object which made my like much easier. Following is the program using HASH object to match 1:10 cases with controls. We can not use PSMatch, it is completely different than the match we do directly by comparing variables.   data controls; set controls; matchkey = catx('_', gender_control , age_control); proc sort data = controls out=controls; by matchkey; run;   data cases; set cases; matchkey = catx('_', gender_case , age_case); proc sort data = cases out=cases; by matchkey; run;   data matched_ctrls(keep=id_case gender_case age_case id_control gender_control age_control  );   Length id_control  $20 age_control 8 gender_control  $2  matchkey $20;   if _N_ = 1 then do;                 declare hash controls(dataset:"controls", multidata: "Y");                 controls.defineKey("matchkey");                 controls.defineData("id_control","age_control","gender_control", "matchkey");                 controls.defineDone();                   declare hash used_controls();                 used_controls.defineKey("id_control");                 used_controls.defineDone(); end;   do until (last.matchkey);                 set cases;                 by matchkey;                   match_count = 0;                 rc = controls.find(key:matchkey);   do while(rc = 0 and match_count < 3 );                   if used_controls.check(key:id_control) ne 0 then do;                                 output;                                 match_count+1;                                 used_controls.add();                 end;                   rc = controls.find_next();                 end;                   end;                 run;   ... View more