A total of 80 free-range Iberian pigs reared with acorns and grass in eight different free-range systems (n = 10) in the southwest of the Iberian Peninsula were used to determine the relationship between fatty acid, tocopherol, and neophytadiene subcutaneous fat composition. The pigs were fed extensively for 79.1 ± 9.5 d from 110.9 ± 11.9 kg live weight at the beginning of the final fattening phase to 175.0 ± 15.9 kg slaughtered weight. Quercus suber and Quercus rotundifolia acorns were characterised by a high content of C18:1n-9 (58.3 and 63.1%, respectively) and γ-tocopherol [43.7 and 43.0 mg kg⁻¹ dry matter (DM), respectively], while grass exhibited a high content of C18:3n-3 (42.5%), α-tocopherol (366.5 mg kg⁻¹ DM) and neophytadiene (136.2 relative area units). The C18:1n-9 (54.4%–57.7%) and γ-tocopherol (2.7–4.1 mg kg⁻¹ DM) contents in subcutaneous fat from Iberian pigs differed (p < 0.001) between the free-range systems studied. Pasture intake had a significant effect (p < 0.01) on subcutaneous fat content of C18:3n-3 (0.5%–0.8%), α-tocopherol (7.8–13.1 mg kg⁻¹ DM) and neophytadiene (2.6–6.3 relative area units). However, the results demonstrated no correlations between accumulated levels of these compounds throughout the free-range period. In conclusion, the absence of correlations corroborated the heterogeneity of extensive rearing systems, with variations between years and geographical areas where the Iberian pigs were reared.