THE NATIONAL INSTITUTE OF DRUG ABUSE, DIVISION OF RESOURCE DEVELOPMENT, FORECASTING BRANCH, UNDERTOOK THE INVESTIGATION OF DRUG ABUSE PATTERNS WITHIN THE CHULA VISTA, CALIFORNIA STANDARD REPORTING AREA FROM SEPTEMBER 1978 THROUGH MARCH 1979 TO DEMONSTRATE HOW THE GEOCODING, COMPUTER MAPPING, AND AUTOMATED PLOTTING OF THE GBF/DIME SYSTEM CAN AID IN ANALYZING PATTERNS OF DRUG USERS ON A LOCAL AND REGIONAL SCALE. THE FOLLOWING DRUG ABUSE INDICATORS WERE USED AS MEASURES OF CHANGE: (1) DRUG ABUSE TREATMENT ADMISSIONS, (2) HEPATITIS (TYPE B) CASES, (3) DRUG-RELATED DEATHS, (4) NONFATAL EMERGENCY ROOM EPISODES FOR DRUG ABUSE, AND (5) DRUG LAW VIOLATION ARRESTS. DATA SOURCES INCLUDED AN OUTPATIENT DRUG-FREE CLINIC, DATA ON HEPATITIS (TYPE B) CASES FROM THE DEPARTMENT OF PUBLIC HEALTH OF SAN DIEGO COUNTY, THE CORONER'S OFFICE OF SAN DIEGO COUNTY JAIL (FOR DRUG VIOLATION ARRESTS). DATA WAS PROGRAMMED FROM A STANDARDIZED RECORD FORMAT CONTAINING VITAL INFORMATION ON EACH SUBJECT. THE RESULTANT MASTER DRUG TAPE WAS MATCHED AT A RATE OF 85 TO 90 PERCENT BY ADDRESS RANGE TO THE ADMATCH PROGRAM FOR MATCHING ADDRESS TO THE DIME FILE FOR THE CHULA VISTA AREA. NOTABLE RESULTS WERE A DISPLAY OF SMALL AREA DRUG PATTERNS AND A NONOVERLAPPING ESTIMATE FOR DRUG-RELATED DEATHS. IT IS RECOMMENDED THAT GBF/DIME BE APPLIED TO INTRA AND INTER-CITY CORRELATES OF DRUG USE, TO OTHER VARIABLES (E.G., PROPERTY CRIME), AND TO OTHER FIELDS SUCH AS MENTAL AND OTHER HEALTH CARE FIELDS. TEN REFERENCES, FIGURES, AND TABLES ARE PROVIDED.