The genetic structure of Nigerian indigenous pigs (NIP) and crossbred pigs were investigated using polyacrylamide gel electrophoresis. A total of 79 NIP blood samples were collected from three different locations within South-western Nigeria namely, Igbara Odo, Ekiti State (33 samples), Ogbooro, Oyo State (30 samples), and Institute of Agricultural Research and Training (IAR&T), Oyo State (16 samples). In addition, 41 crossbred pig blood samples were collected from the Teaching and Research Farm (T&R Farm), Obafemi Awolowo University, Ile-Ife. The blood serum samples obtained from the pigs were subjected to Sodium dodecyl sulphate (12%) SDS-PAGE gel electrophoresis. A total of 19 protein loci were scored for the NIP and 16 for crossbred samples. The SDS-PAGE electrophoretic profiles were analysed using PAST package (2005) to determine genetic similarity coefficients and construct phylogenetic dendrograms using Nei’s standard genetic distance. Ogbooro NIP samples showed a very high level of genetic similarity (91%) while IAR&T was 87% whereas Igbara Odo was 56%. The T&R Farm crossbred pigs showed 81%. The total local pig samples from the three locations gave a high genetic similarity coefficient of 84% confirming their genetic relatedness. The high genetic similarity observed in the indigenous pig samples in Ogbooro indicated a level of inbreeding of pig stocks in this locality which can be conserved as a genetic resource for breeding programmes for pure NIP in the future. Key words: Animal genetic resources, conservation, Nigeria indigenous pig, electrophoresis