Contact angle measurements constitute the most widely-used method to assess interfacial free energies between a solid and a liquid. Axisymmetric drop shape analysis by profile, ADSA-P, has been suggested as an alternative method, which might have, both on experimental and on fundamental grounds, major advantages especially for the determination of gamma(sl) of biological substrata in particular. Here, solid-liquid interfacial free enegies gamma(sl) of bovine serum albumin coated substrata as derived from ADSA-P experiments are compared with those calculated from measured contact angles of liquids on the bare substrata and on the dried, adsorbed protein layers, while making use of the equation of state, the geometric-mean equation, both neglecting and accounting for spreading pressures, and the Lifshitz-van der Waals/acid-base approach to convert the contact angle data into surface free energies. During ADSA-P, the protein was adsorbed from a protein solution droplet placed on the substratum. The liquid surface tension gamma(lv) and the contact angle theta were measured as a function of time after positioning of the droplet and used to calculate the corresponding values for gamma(sl)(t) using the Young equation. For the contact angle measurements on dried, adsorbed protein layers, the substrata were coated in advance and air-dried and sessile drop contact angles on both the bare and the coated substrata were measured with a variety of liquids and used for the calculation of gamma(sl) according to one of the thermodynamic approaches mentioned. Statistical analyses of gamma(sl) and DELTAgamma(sl) data showed that, considering both bare and protein-coated substrata together, the geometric-mean method was internally consistent with ADSA-P and that the equation of state and the Lifshitz-van der Waals/acid-base approach corresponded well with ADSA-P on an independent basis (P less-than-or-equal-to 0.05). This simultaneously indicates that contact angle measurements on dried, adsorbed protein films have a relevance with regard to polymer/water/protein interactions. Considering the t = 0 data as representative for the bare substratum surface shows that the internal consistency of the approach accounting for spreading pressures is higher on poly(methyl methacrylate) than on fluoroethylenepropylene-Teflon as compared with those of the other approaches. This emphasizes that accounting for spreading pressures becomes more important as the materials surface free energies increase.