Determinants of physician utilization were examined using a three-generational sample of Mexican-Americans in San Antonio. A typical version of Andersen's causal behavioral model was moderately successful in predicting physician utilization in the middle and older generations and less successful in the younger generation. Consistent with the literature, need factors (health indicators) tended to affect utilization most directly. The authors also examined whether acculturation into the larger society positively influenced utilization regardless of need, as the literature suggested. While three separate measures of acculturation had no independent effects on physician utilization, acculturation did affect utilization indirectly via the need variables in the middle generation, although these effects were not consistently in the direction of greater utilization. Generational differences in determinants of physician utilization arc discussed particularly in relation to the model's greater relevance for the middle and older generations.