A framework is outlined for testing empirically whether utilization of and access to public-sector GPs in Spain in 1993 was consistent with the twin criteria of horizontal and vertical equity, where these are defined with respect to need. Vertical (horizontal) inequities in access are assessed by including interactions between determinants of access and need (non-need) variables in a utilization equation. Findings are consistent with the principle of vertical equity in the utilization of GP services, but are not consistent with horizontal equity. Travel time for individuals who did not visit their GP are imputed but it is not a significant determinant of utilization or access. However, caution is expressed when interpreting these findings, as they may be contaminated by biases arising from unit non-response, measurement error and simultaneity. The paper concludes with a set of recommendations for future studies.