Objective:To examine the impact of the introduction of dry chemistry pathology in general practice.Design and setting:A two‐period crossover trial in two groups of general practices.Participants:Twenty‐eight general practices with an interest in participating in a trial of the new technology were selected from practices related to the coordinating hospitals.Intervention:Each practice was observed in its usual operation for one of the two study periods and observed using a dry chemistry analyser during the other.Main outcome measures:Laboratory pathology tests and analyser tests were recorded during the study period. General practice records were searched to assess the impact of dry chemistry pathology on the detection of new disease (anaemia) and the control of existing disease (diabetes; and hyperkalaemia or hypokalaemia). Questionnaires were given to patients and general practitioners to assess their perceptions of the new technology. Imprecision of the analysers was assessed by use of their internal control material and inaccuracy was assessed by split sample analysis in comparison with standard laboratory tests.Results:Use of analysers was associated with a 2% non‐significant reduction in the use of laboratory tests. For those tests with a direct analyser equivalent, there was a 9% and 13% reduction in biochemical and haematological tests respectively. However, there was a 46% increase in the total number of biochemical tests ‐ by laboratory or analyser ‐ during the period when analysers were available. No effect on the detection of new disease or the control of existing disease was observed. Patients rated analysers highly and rated laboratory tests less highly when analysers were available. General practitioners typically reported that the analysers made a minor contribution to their practice and did not fit in easily. The level of analytical reliabiiity of the analysers was not always acceptable.Conclusion:General practices varied greatly in their use of the analysers. This experience of dry chemistry pathology in general practice suggests that its application is limited.