sThe rate of photosynthesis q/Jacquemontia paniculata leaves and the effect of different concentrations of paraquat solutions on the rate of photosynthesis were studied using the oxygen-electrode Clark-type. The mean value of the photosynthetic rate o/Jacquemontia paniculata leaves at room temperature was found to be 60.24 ± 4.20 imol O2/'dm2/hour. The optimum concentration of paraquat solution to be used as a sprayed herbicide forJacquemonu'apaniculata leaves is 0.0054 M.