Although Virtual Population Analysis (VPA) (Gulland, 1965) and related procedures have been in widespread use for many years, there have been few investigations of the statistical properties of the VPA estimators. This paper introduces approximate variance estimators for the VPA cohort size and fishing mortality rate estimators for the case of simultaneous and possibly dependent errors in all input parameters. These approximate variance estimators are tested by Monte Carlo simulations. It is shown that they are biased but reasonably accurate. They are then applied to published data for the purpose of illustrating the effects of various levels and combinations of input parameter inaccuracies upon the precision of the VPA estimates. It is also shown that trends in the variability of successive output parameters are dependent on the levels of estimation error in the input parameters. The coefficients of variation in the cohort size and fishing mortality rate estimates will, however, be of the same order of magnitude as the coefficients of variation in the terminal fishing mortality rate, natural mortality rate, and the catches-at-age.