Barbiturates are derivative of barbituric acid which acts as central nervous system depressant. The primary detection of barbiturates is carried out by the presumptive tests viz. Dille Koppanyi test and Zwikker’s test. A comparative study was done in order to determine whether there are any differences in the results of the two tests and to find out the test with more consistency. Drug samples containing Phenobarbital viz. Gardenal-30 and Gardenal-60 were used in the study. Solution mixtures of 9 different ratios were prepared in the ratios 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2 and 9:1 comprising stock solution of Phenobarbital and solvent (Methanol AR). Both the tests were performed upon the samples at different proportions on spot tile and test tubes and the absorbance values (given by UV/VIS Spectrophotometer) for all the various test results at different concentrations were compared. The study demonstrated that Dille-Koppanyi test showed better results after interpretation of the absorbance values using Independent sample ‘t’ test and Coefficient of variation. A mean value of 2.85 was found for Zwikker’s test and a mean value of 3.19 for Dille-Koppanyi test. A significant difference of p<0.01 was obtained between the results from the two tests. Further, a better consistency was found from the absorbance values of Dille-Koppanyi test as compared to the absorbance values of Zwikker’s test which is shown by the values of Coefficient of variation that was found to be higher for Zwikker’s test (2.00 and 5.86 for Gardenal-30 and Gardenal-60 respectively) and lower for Dille-Koppanyi test (0.78 and 2.26 for Gardenal-30 and Gardenal-60 respectively). In cases of trace amounts of drug sample being recovered from crime scene suspected to be barbiturate, primary detection can be efficiently done directly using DilleKoppanyi test instead of Zwikker’s test which will lead to a better outcome in the investigation.