Genetic parameters were estimated for total number of piglets born (CNS), number of piglets weaned (DS), lean meat content (LM) and average daily gain from birth to the end of the field test (PŘIP) in Czech Large White (ČBU) and Czech Landrace (CL) using four-trait animal models. The following heritabilities were estimated (first number: ČBU, second number: ČL): 0.10 and 0.09 for CNS, 0.09 and 0.07 for DS, 0.39 and 0.36 for LM, 0.21 and 0.18 for PŘIR. High genetic correlations (approximately 0.85 for both breeds) were estimated between the two litter size traits. All remaining genetic correlations for ČL were less than 0.20. A negative correlation of approximately -0.25 was estimated for ČBU between average daily gain and both litter size traits.