A computerized falling head permeameter system was used to measure hydraulic conductivity of pervious concrete from samples taken from three different field-placed slabs with known porosities. Important differences between samples were found, and these follow the same trend as differences in porosity. The relationship between porosity and hydraulic conductivity is suggested as a tool for designing pervious concrete pavements as a stormwater pollution best management practice. A quantitative relationship between porosity and hydraulic conductivity was established based on the Carman-Kozeny equation for the samples tested. Samples with porosities less than 15% presented limited hydraulic conductivity. Important considerations on the measurement of hydraulic conductivity of pervious concrete samples are discussed, and the Ergun equation is used to explore the flow regime inside pervious concrete samples.