Ten different benchmark tests have been performed for different versions of the Gaussian as well as for the Cadpac ab initio program package on nine different computers ranging from vector supercomputers to workstations. The test jobs form a set representative of the most frequent applications of ab initio quantum chemistry, i.e. single point and gradient calculations at the SCF and MP2 levels of theory as well as SCF second derivative calculations for both closed-shell and open-shell species (the molecule of bicyclobutane and its radical cation calculated using the 6-31G* basis set). The relative performances of the different programs and machines exhibit considerable variation as a function of the type of calculation and the present results should prove useful for the selection of the most efficient program and computer for a given application. Notably, modern RISC-based workstations were found to be similar or sometimes even superior in performance to most mainframes for calculations of the type represented by the test jobs