Quality control of the main constituents was conducted on four finished herbal drug products, one-batch each in soft gelatin capsules manufactured by an American Company including Devil's claw, Valerian, Twinlab powerman Yohimbe power and Korean white Ginseng root. Pharmacopoeial constants and elemental analysis were determined. The results obtained revealed that there is no significant difference from the constants published in different Compendia. The results indicated no adulteration or substitution in these herbal preparations, and no pesticidal residues were detected in all samples under investigation. The results of viable count revealed that all the four herbal preparations were free from pathogenic organisms and the limits of aerobic and yeast not exceed the acceptable limits. The results obtained for the detection of aflatoxins revealed that the fungi isolated from the four herbal preparations showed no fluorescence in UV after growing on Sabauraud medium, the chloroform extracts of the four preparations when subjected to HPLC analysis, confirmed absence of aflatoxins. The obtained Pharmacopoeial values are around the recorded values. HPLC, qualitative and quantitative determinations of the major constituents were in agreement with the reported data.