Synthesis of luciferase, an alpha beta dimer, occurs during a relatively short period of time near the end of exponential growth of Beneckea harveyi. The rates of synthesis of the individual alpha and beta chains of luciferase are compared by quantitating the molar ratio of total cellular alpha to that of beta at different growth stages. The addition of exogenous alpha or beta subunit to crude lysates of cells taken prior to and during the luciferase induction produces no increase in luciferase activity. This result, together with previous evidence that there are no antigenically cross-reacting precursors, allows us to conclude that luciferase alpha and beta chains are synthesized pari passu, i.e. in equal proportions, and exist primarily in the alpha beta dimeric form. It is also shown that insoluble sedimentable cellular materials contain no detectable luciferase subunits.