It has been previously demonstrated that luciferase synthesis in the luminous marine bacteria, Beneckea harveyi and Photobacterium fischeri is induced only when sufficient concentrations of metabolic products (autoinducers) of these bacteria accumulate in growth media. Thus, when cells are cultured in liquid medium there is a lag in luciferase synthesis. A quantitative bioassay for B. harveyi autoinducer was developed and it was shown that many marine bacteria produce a substance that mimics its action, but in different amounts, (20–130% of the activity produced by B. harveyi) depending on the species and strain. This is referred to as alloinduction. None of the bacteria tested produced detectable quantities of inducer for P. fischeri luciferase synthesis. These findings may have significance with respect to the ecology of B. harveyi and P. fischeri.