Several estimators of coancestry from molecular information were compared. The data came from 63 iberian pigs of the strains Guadyerbas and Torbiscal with the complete genealogy known since 1945. The markers used were 32 microsatellites distributed among the 18 autosomes. The estimators calculated were: 1) L&H1 y L&H2 proposed by LI and HORVITZ (1953); 2) L&R proposed by LYNCH and RITLAND (1999); 3) Q&G proposed by QUELLER and GOODNIGHT (1989); 4) RIT, proposed by RITLAND (1996). Besides, the molecular and the genealogical coancestry was also calculated, the last one using the complete pedigree. Important discrepancies were found between the estimations obtained with molecular information and the coancestries calculated in the genalogical analysis, being the first much smaller. The correlation between the estimations and the genealogical values was also calculated. This correlation was high, between 0.91 and 0.74 for the different estimators when all the animals were considered and therefore a wide range of coancestries ocurred. However, the correlation decreases until values of 0.60 and 0.30 for the Guadyerbas and Torbiscal populations, respectively when they were analysed separately. Finally, the possible causes of the discrepancies are also discussed.