IT IS INDICATED THAT THE PURPOSE OF THIS STUDY IS NOT TO RECOMMEND ANY PARTICULAR ANALYTICAL SCHEME SUITABLE FOR HEROIN'S IDENTIFICATION, BUT RATHER TO PROVIDE DATA USEFUL FOR EVALUATING THE SPECIFICITY OF PRESUMPTIVE ANALYTICAL TESTS FREQUENTLY USED BY CRIME LABORATORIES FOR THE IDENTIFICATION OF HEROIN. THE ULTIMATE SELECTION OF ANALYTICAL PROCEDURES FOR HEROIN IDENTIFICATION DEPENDS ON NUMEROUS FACTORS, SUCH AS THE QUANTITY AND PURITY OF THE SAMPLE, THE NATURE OF THE ADULTERANTS AND DILUENTS PRESENT, THE EXPERIENCE OF THE ANALYST, THE AVAILABILITY OF ANALYTICAL TECHNIQUES AND INSTRUMENTATION, AND THE AMOUNT OF TIME AVAILABLE TO PERFORM THE ANALYSIS. IF SPECIFICITY WERE THE SOLE CRITERION FOR CHOOSING A PARTICULAR TEST, THE INFRARED SPECTROPHOMETRY TEST IS RECOMMENDED, ALTHOUGH IT IS FAR FROM BEING THE MOST POPULAR AMONG CRIME LABORATORIES. RECOGNIZING THAT THE COMPOUNDS MOST LIKELY TO BE MISTAKEN FOR HEROIN ARE THE MORPHINE DERIVATIVES HAVING A MOLECULAR STRUCTURE CLOSELY RELATED TO HEROIN, THIS EXPERIMENT WITH HEROIN AND 56 MORPHINE DERIVATIVES AMPLY DEMONSTRATES THAT SUCH MORPHINE COMPOUNDS CAN BE DISTINGUISHED FROM HEROIN AND THAT A VALID AND LEGALLY DEFENSIBLE ANALYTICAL SCHEME CAN BE DEVISED FOR HEROIN'S IDENTIFICATION WITH THE PRUDENT SELECTION OF A COMBINATION OF PRESUMPTIVE TESTING PROCEDURES. THE ANALYTICAL PROCEDURES EVALUATED INCLUDED TWO COLOR TESTS, FIVE MICROCRYSTALLINE TESTS, FOUR TLC (THIN-LAYER CHROMATOGRAPHY) SYSTEMS, FOR 6C (GAS CHROMATOGRAPHY) SYSTEMS, AND ULTRAVIOLET AND INFRARED SPECTROPHOTOMETRY. GRAPHIC AND TABULAR DATA ARE PROVIDED, AS ARE REFERENCES. (RCB)