The ostrich industry suffers from a high rate of embryonic mortality during artificial incubation of eggs. Data from 34 285 eggs were used to derive 969 female-year records for evaporative water loss (WL), treated as a trait of the female. Heritability was significant for WL at a level of 0.40–0.41 (both after 21 and 35 days of incubation). WL at 21 and 35 days was negatively correlated on the genetic level with chick weight at hatching (–0.84 and –0.81, respectively). Shell deaths did not exhibit high levels of genetic variation (0.06), but were affected by the permanent environment of the female (0.33). Shell deaths were correlated with WL on a genetic level (–0.34 to –0.41), but the estimated genetic correlations were associated with high standard errors and are, therefore, not very robust. Further research is needed to obtain more accurate genetic relationships between traits influencing incubation.