The growth of Norway lobster (Nephrops norvegicus) from the bay of Biscay was modelled through the succession of moults and intermoult periods. First, parameters related to each of these processes were estimated for each sex and maturity stage. Moult increment was modelled as a linear function of carapace length, and regression parameters were estimated. For females, intermoult period was assumed to depend on maturity stage whereas for males it was assumed to be constant throughout their life. Mean intermoult periods were estimated from radiometric data. The estimations relied on bootstrap procedures that take into account both measurement error and individual variability. In a second step, 500 individual growth curves were simulated using previous parameter estimates. Finally, an age-length key was calculated from simulation outputs, yielding median age-at-length as well as corresponding confidence interval.