Epi-fluorescence video microscopy and digital image processing were used to evaluate the effects of three novel anti-platelet agents namely GT-12/I.2HBr (GT-12/I), A4.2HBr and IC, a series of compounds containing the $-3−carboxylicacidpiperidinemoietyastheirfunctionalgroup,onplateletaggregation.GT−12/Iwasevaluatedataconcentrationof100\mu$M so that it could be used as a reference compound against which the effects of A4.2HBr and IC could be compared. Results show that at this concentration GT-12/I inhibited platelet accumulation by 59.0 ± 3.8% whereas A4.2HBr, the more hydrophobic molecule, inhibited aggregation by 73.5 ± 1.9% at the same concentration. This confirms earlier predictions that the optimization of hydrophobicity within a compound maximizes its inhibitory potential. Stereochemistry, however, seems to dominate over all other effects as it was observed that IC, an enantiomer of GT-12/I, drastically reduced platelet aggregation by 84.8 ± 2.8%. (Abstract shortened with permission of author.)