The theories of optimal H∞ control and three other optimal measures are applied to the study of biochemical pathways. The additional optimal measures include the H2 energy-to-peak and the peak-to-peak optimal measures. Based on a static output-feedback configuration, the sensitivity of the pathways to various system uncertainties that include uncertainties in the rate constants and the concentrations of the enzyme involved is addressed. The results are applied to the study of the possible optimality in the above measures of both the threonine synthesis pathway and the glycolytic pathway. It is shown that the H∞ and the peak-to-peak optimal measures are better suited to describe the sensitivity of these pathways to various parameter uncertainties.