OBJECTIVES To describe the active principles (AP) marketed in Spain from 1992 to 2002, to determine their characteristics, and to find whether they supposed genuine therapeutic advances (TA). DESIGN Transversal, descriptive study. MAIN MEASUREMENTS The degree of TA in the AP analysed was studied with the classification used by the FDA (A*: exceptional therapeutic novelty; A: important therapeutic novelty; B: modest therapeutic improvement; C: null or very little therapeutic improvement, corresponding to "me-too" drugs; and D: not classified), the context of use and the price. RESULTS 369 new AP were marketed. 3.5% were in group A*, 11.9% in A, 30.1% in B, 49.3% in C, and 5.1% in D. 42.3% corresponded to AP used in hospitals for therapy or diagnosis. Significant differences were found (P<.05) on comparing the degree of TA and the context of use, such that more AP in the A/A* (32.6%) and B (44.0%) groups were found in AP used in hospital therapy and diagnosis than in AP used in primary care and generally (5.3% in the A/A* groups and 23.4% in group B). Only 11 AP of the A/A* groups were used in primary care. The cost per defined daily dose was 17.6 euros; and the new AP in group C were dearer than already existing alternatives in 93.4% of cases. CONCLUSIONS Real TA are few in number and preferentially used in hospitals. Almost all the new AP are "me-too" drugs and are dearer than already existing alternatives.