Calculations show that as the residual stress increases, the number of magnetic domains in titanomagnetite at first increases and subsequently decreases, and large residual stress causes laminar domain structures in Ti-rich titanomagnetite, as is often observed. In addition, large residual stress significantly decreases the number of domains, as is also observed. One anticipates that large residual stress also exists in most pure magnetites, but theory and observations are inadequate to confirm this expectation. We conclude that the presence of a large macrostress and possible systematic errors in the observational estimates of the number of domains observed explains the current discrepancy between domain observations and theory for titanomagnetite grains. ¿ American Geophysical Union 1995