The soil fertility of a biodynamic avocado plantation in Tenerife and its relation to mineral nutrition was studied and compared with similar variables investigated previously in conventional plantations. The surface soils of the biodynamic plantation showed pH, organic matter and available P, Ca, Mg and K averages significantly higher than those of the conventional plantations. As regards the foliar nutrient levels, the N, P, K, Mg and Cu averages were similar in both types of plantations, while the average foliar Ca and Mn values were significantly lower in the biodynamic avocados, although they fell within the range considered normal. On the other hand, the Zn average was significantly greater in the biodynamic plantation.