A model immunoassay between concanavalin A (antibody) and yeast mannan (antigen) was investigated using a microcomputer-controlled flow injection analysis (FIA) manifold with turbidimetric detection at 400 nm. The automated injection procedure gave good precision for a turbidimetric method and the stop-flow merging zones technique gave an acceptable sample throughput (50 samples per hour) with minimum consumption of sample (30 µl). The system described could therefore be used routinely for immunoprecipitin analysis in clinical laboratories, e.g., lgG in human serum, and also to study kinetic aspects of such reactions.