Two sets of commercial PL/I programs are studied. One set represents programming practice before the introduction of structured programming techniques and the other set after their introduction. The use of these new methods is found to make a measurable difference on the quality of the programs. A few minor changes in the use of PL/I are noted. Substantial modifications to the control structure of the programs are measured. Also, some improvements in the qualitative aspects of the two sets are discussed. Although, they are much improved, further alterations can make the programs still better. The time and training required to introduce structured programming techniques will begin paying dividends within six months.