A laser densitometer and a video densitometer were used to evaluate neutrophil chemotaxis slides which were also assessed by the standard microscopic technique. A linear relationship was observed between cell number per high power field (HPF) and peak height by laser densitometry (r2 = 0.66) or peak area by video densitometry (r2 = 0.81). For wells containing more than 20 cells/HPF the least variability was observed with video densitometry. Quantitative results from neutrophil chemotaxis assays performed in 48-well microchambers can be obtained rapidly and conveniently by the use of commercially available video densitometers.