The term intra-urban migrant lifeline refers to the sequence of residential movements made by a household within a single urban area. This study examines spatial aspects of lifelines and the relationship between such aspects and the spatial structure of the city. Spatial aspects are defined in terms of distance, directional, and sectoral biases. A variety of techniques for identifying such biases are critically discussed. The approach applied is one that transforms the spatial pattern of migrations so as to accent the spatial biases in question. Measurement of the biases is accomplished by application of standard ellipse techniques to the transformed distributions. Data for the study traces migrant lifelines for a sample of households in Cedar Rapids, Iowa, for the period 1950 through 1965. Differences in locational and social-economic characteristics of households are shown to be reflected in the spatial morphology of their respective lifelines. In general the migrant lifelines show a fairly restricted distance bias, a directional bias towards the center of the city, and a low degree of sectorality. This is in contrast to expectations generated by previous work on lifelines. Reconciliation of the findings here with previous findings employs a model that considers both the space preferences of intra-urban migrants and the set of vacancies available to them.