The covariance structure was estimated by REML for a joint genetic evaluation of production and reproduction traits for Czech Landrace (58258 records) and Czech Large White (167161 records) pigs using four-trait animal models. The following traits were analysed: lean mean percentage (LM) and life-time average daily gain (in g/day) in the field test (ADG), number of piglets born alive in the 1st litter (NBA1) and in the 2nd and subsequent litters (NBA2).