Transport of linuron, imidacloprid and bromide along soil columns and field lysimeters. Undisturbed soil columns (65 cm high x 15 cm diam.) were used in a greenhouse experiment to study the effect of rainfall and mode of application on leaching pattern of linuron and imidacloprid. Two simulated rainfall amounts (288 mm and 496 mm) distributed over a one month period and two modes of application (sole or combined application of the two pesticides) were studied. Linuron did not leach below 65 cm of the soil columns. Imidacloprid was leached in trace amount below 65 cm soil columns (less than 1,5/ of applied a.i.). Under field conditions, linuron was detected in percolated water below 1 m depth lysimeters at concentration less than 4 microg per liter. Imidacloprid was detected at concentration less than 3 microg per liter in percolated water below 1 m depth. Bromide ion was leached at 62 to 88/ of the applied mass on soil columns or field lysimeters. The elution pattern of bromide ion suggests the presence of preferential flow paths.