The gestation period in Van cats is between 54 and 68 days, with high individual differences. Because of this variability, the date of birth cannot be predicted precisely, while the factors influencing the gestation period in Van cats have not been examined previously. The aim of this first study was to evaluate the influence of age, body weight of the dams and the litter size on the gestation period in Van cats. 28 Van cats aged one to nine years were used for this study. The body weight of the cats in the oestrus at the beginning of the study varied between 2.1-4.1 kg (3.1 +/- 0.6 Kg). The time from first mating until birth was regarded as being the gestation period. Correlations were determined between the duration of pregnancy and the age and body weight of the females as well as litter size. The mean duration of pregnancy in all 28 Van cats was 63.6 +/- 3.6 days (min. 54 days, max. 68 days) with a mean litter size of 3.4 +/- 1.3 kittens (min. 1, max. 6). No correlations could be found between the factors examined meaning that the duration of pregnancy does not depend on the age or body weight of the dams or on the litter size. It must be concluded that other factors may cause this high variability of pregnancy duration in Van cats and these still need to be investigated.