The land slug Deroceras laeve shows an enormous variation in life-history traits. Here, we compared several life-history characters (i.e. length of the prereproductive period, growth during the egg-laying period, number of eggs, hatching success) within and among five selfing homozygous multilocus genotypes (MLG) and investigated a possible trade-off between the number of eggs produced during the egg-laying period and growth during the egg-laying period. Life-history traits were highly variable. There was no significant correlation between slug size and fecundity. Slugs that matured early produced more eggs than slugs that matured later. Life-history traits were significantly different among MLGs, suggesting that genetic factors may affect and explain at least part of the variation in life-history traits in D. laeve. Finally, we found no evidence of a trade-off between the number of eggs produced during the egg-laying period and growth during the egg-laying period.