A quantitative structure-activity relationship (QSAR) study of a wide series of structurally diverse alpha1-adrenergic receptor antagonists was performed using the CODESSA (Comprehensive Descriptors for Structural and Statistical Analysis) technique. Theoretical descriptors derived on a single structure and ad hoc defined size and shape descriptors were considered in the attempt of describing information relevant to receptor interaction. The relative effectiveness of these two classes of parameters in developing QSAR models for native (alpha1A and alpha1B) and cloned (alpha1a, alpha1b, and alpha1d) adrenergic receptor binding affinity, functional activity of vascular and lower urinary tract tissues, and in vitro and in vivo selectivity was evaluated.