A prediction of drop coalescence behavior based on HLB (Hydrophile-Lipophile Balance) of extractants has been examined for liquid-liquid systems using industrial extractants. With a video camera, time course of coalescence was observed for droplets formed at the top of adjacent nozzles in water. Drop coalescence behavior in a liquid-liquid system has been monitored for ten systems containing industrial extractants, e.g. PC88A (2-ethylhexyl-phosphonic acid mono-2-ethylhexyl ester), D2EHPA (di(2-ethylhexyl)phosphoric acid), TBP (tri-n-butyl phosphate), MIBK (methylisobutyl ketone), LIX84I (2-hydroxy-5-nonylacetophenone oxime), LIX860IC (5-dodecylsalicylaidoxime), TOA (trioctylamine), Et2CO (diethylketone), BA (benzoylacetone) and TOPO (tri-n-octylphosphine oxide). Investigated parameters are the concentration and HLB of the extractants. Similar experiments were conducted with surfactants, SPAN systems for which HLB values are known. Average times needed for coalescence for the extractants are compared with those for the surfactants. Average times needed for coalescence decrease with the increase in the extractants concentration and HLB values of the extractants. HLB of the extractants works as one controlling factor for drop coalescence.