Modern instruments and techniques used to collect nutrient data at sea may amass huge data sets from discrete samples and continuously monitored sample streams. The volume and format of data produced by some sampling techniques preclude data analysis by manual methods. However, the analysis of a wide variety of sample types also makes the use of fully automatic data analysis inappropriate, so that a flexible approach to data analysis is required. Although at sea autoanalyser chemistry methods are thoroughly described in the literature, little information is available on data handling procedures. A suite of computer programmes has been developed to cope with a wide variety of autoanalyser nutrient data. Here we describe the basic design of data acquisition and sub-sampling programmes and methods of operation.