Abstract This paper compares estimates of the signal-to-noise ratio(SNR) required by imaging spectrometers for the estimation of foliar biochemical concentrations and the SNR currently achieved by the Airborne Visible/ Infrared Imaging Spectrometer (AVIRIS). The work was comprised of three sections. Section 1: the SNR required by imaging spectrometers was estimated by modelling three data sets, each of which more closely approximated the data recorded by the AVIRIS. The remaining stages were concerned with estimating the SNR currently achieved by the AVIRIS. Section 2: SNR estimates made as part of instrument calibration were scaled to those that would be expected when viewing vegetation, and section 3: SNR was estimated directly from AVIRIS imagery. The results of these three sections were then compared to assess the SNR performance of the AVIRIS and its utility for the estimation of foliar biochemical concentrations. The SNR of the AVIRIS is planned to double between 1994-5 and while this sensor was barely adequate for the estimation of foliar biochemical concentrations in 1992-3 it should be more than adequate from 1995 onwards.