We review the application of numerical techniques to investigate mathematical models of phenomena in the biosciences using delay di erential equations. We show that there are prima facie reasons for using such models:(i) they have a richer mathematical framework (compared with ordinary di erential equations) for the analysis of biosystems dynamics,(ii) they display better consistency with the nature of the underlying processes and predictive results. We now have suitable computational techniques to treat numerically the emerging models for the biosciences.