The objectives of this study were to determine the selection potential (genetic variation) of sow efficiency traits (prolificacy, longevity), to understand the co-responses (genetic correlations) among sow efficiency traits and other economically important traits (performance, carcass quality, and meat quality), and determine the feasibility of developing breeding value estimates for sow efficiency traits. To meet the objectives, five separate studies were carried out. The prolificacy traits evaluated were total number of piglets born, number of piglets born alive, number of piglets weaned, number of stillborn piglets, percent of stillborn piglets, number of piglets dead during suckling, percent of dead piglets during suckling, gestation length, age at first farrowing, and farrowing interval. The studied longevity traits were lifetime prolificacy (number of piglets per sow s lifetime), length of productive life, and leg conformation (overall leg action, and six symptoms of leg weakness). The results showed that the sow efficiency traits are generally lowly heritable. The only exceptions are buck kneed on fore legs (conformation trait), age at first farrowing and gestation length, which are moderately heritable. Among leg conformation traits, there was a strong favorable genetic correlation between buck-kneed on the fore legs and overall leg action, whereas no clear genetic association were found between the other leg conformation traits. Moreover, the overall leg action was favorably correlated with length of productive life, indicating that the selection for leg conformation will improve sow longevity through indirect selection. The results showed further that length of productive life and lifetime prolificacy are genetically favorably associated with litter size and farrowing interval. The most substantial unfavorable correlation among sow efficiency traits exists between litter size and piglet mortality. The current results indicated clearly that the selection only for number of piglets born (totally or alive) will lead to increased piglet mortality. Therefore, the selection should be simultaneously for litter size and piglet mortality. In general, there was a tendency for sow efficiency traits to be favorably correlated with performance traits, and unfavorably with carcass lean and fat percentages, whereas there was no clear association between sow efficiency and meat quality. Accuracy of estimated breeding values may be improved by accounting for genetic associations between prolificacy, longevity, carcass, and performance traits in a multiple trait analysis. Concerning the validity of repeatability model, it appeared that the genetic correlations among litter size between the first and later parity records were lower than the correlations between later parities. All genetic correlations for farrowing interval among different parities were lower than one. These correlations seem to indicate that the litter size from first and later parities, and farrowing interval between all parities should be treated as separate traits in breeding value estimation. In the evaluation of longevity, the estimated heritabilities for length of productive life obtained from linear model analyses were clearly lower than the ones obtained from survival analyses. The higher heritabilities are indicative of the superiority of survival analysis when compared to linear model in the analyses of this type of data. Based on the results obtained from the current studies, the routine to evaluate genetic ranking based on BLUP-index for leg conformation has been implemented, and the prolificacy index has been updated. Overall leg action score and buck kneed on fore legs are the traits included in the leg conformation index. In the updated prolificacy index, the selection is for total number of piglets born, against number of stillborn piglets and piglet loss during suckling, for lower age at first farrowing and for shorter farrowing interval. For the litter size and piglets survival traits, the first parity results and results from the later parities are treated as different traits. Similarly, only the first two farrowing intervals are evaluated, and they are treated as separate traits. Both the prolificacy and leg conformation traits are analyzed with multiple trait animal model BLUP.