With new pest control and bioregulating formulations under development and coming into use to improve spray retention and coverage, concerns have arisen about possible adverse effects on spray solutions due to fluid shear occurring in nozzles. Mathematical models were developed for velocity and shear-rate distributions for incompressible liquid flow through fan-pattern spray nozzles having approximately elliptic outlet orifices. The velocity distribution model was verified with phase/Doppler particle analyzer measurements and computational fluid dynamic simulations. A mean fluid velocity section of the model predicted the axial flow velocity to be 29.03 m/s for an 8002 brass fan-pattern nozzle with 276 kPa operating pressure, compared with a mean measured value of 29.85 m/s, With the shear rate model, it war found that use of an older equivalent-circle model resulted in significant underestimates of shear rates for fan-pattern nozzles. Liquid shear rates at the orifice wall varied with position, and were estimated to fall in the range 1.2 x 10(5) to 7 x 10(5) s(-1) for the spray nozzles studied, depending on nozzle characteristics and operating pressure over a range of 138 to 414 kPa.