Some antibiotics, insecticides, disinfectants and antiprotozoal drugs were tested on Phtophthora melonis Katsura causing fruit and vine rot of pointed gourd in aqueous environment. Antifungal antibiotics viz. validamycin, kasugamycin, griseofulvin, fluconazole and ketoconazole did not have any pronounced effect on mycelial growth, sporangia formation and its germination. None of the eight antibiotics used in this study prevented mycelial growth. No sporangia formation was recorded in five antibiotics viz. streptomycin sulphate + tetracycline hydrchloride, streptomycin sulphate, oxytetracycline hydrochloride, ofloxacin and norfloxacin at 100 ppm. The insecticide, Profenophos prevented sporangia formation and consequently its germination. Copper sulphate (CuSO4, 5H2O) had adverse effect on mycelial growth and sporangia formation. Potassium permanganate (KMnO4), Savlon, Dettol and tinidazole were not good inhibitor for P. melonis. Sporangia did not form in water containing 0.0125g/L chloroquin phosphate - an antiprotozoal drug.