A number of does was classified according to their initial litter size to high (> 6 bunnies, group 1) and low (< 5 bunnies, group 2) in New Zealand White rabbits. Incidence of low litter size in the herd in the present study was 23%. The number of matings/conception, total mortality, corpora lutea/foetus, number and percentage of resorbed foeti were markedly higher in group 2 than in group 1. The litter weight, number of foetuses, implantation sites, and corpora lutea in group 2 showed a marked decrease over group 1. Serum and urine progesterone levels in pregnant rabbits of group 2 were significantly (P < 0.01) lower than in group 1, however, non-efficacious progesterone levels were significantly (P < 0.01) lower in group 2. The zinc content in serum, foetal dry weight and uterine horn dry weight, and serum inorganic phosphate in group 2 were significantly (P > 0.01) lower than in group 1. The litter size was significantly (P < 0.01) correlated with zinc and inorganic phosphate in group 2, while it was correlated with serum and urine progesterone in the two groups. The correlation coefficients were significant (P < 0.01) between urine progesterone and serum zinc and between serum progesterone and inorganic phosphate more frequently in group 2 during the gestation period than in group 1. The treatment of group 2 does with calcium carbonate, sodium phosphate dibasic, and zinc acetate in drinking water improved the serum progesterone, urine progesterone, and non-efficacious progesterone in addition to serum zinc and inorganic phosphate, which led to improvement of the number of matings/conception, litter size and litter weight, and lowered total mortality.