The gestation length (GL) of Tenrecs (Tenrecinae, Afrotheria) is still uncertain. This lack of knowledge also applies to the lesser hedgehog tenrec, Echinops telfairi, the species most commonly bred and maintained in captivity. The animals used in this study were held under controlled conditions (light, temperature and humidity). In order to determine the GL, groups of female tenrecs were subjected to various mating procedures followed by isolation periods of different lengths. A total of n=249 pregnancies were analysed and the number of offspring per litter was 3.29+/-0.09. The length of gestation could be determined in n=199 pregnancies and a mean GL of 67.53+/-0.36 days was calculated. Initial attempts with isolation periods of less than 16 days did not allow to accurately define the GL. Experiments with longer isolation periods and females subjected to only one mating procedure (n=10) revealed a variation in the GLs of 57-79 days. However, in one female a GL of only 50 days was also observed indicating an even greater range in GL variation. There was a statistically significant tendency for shorter GLs in the animals that conceived later in the mating season, but no statistical evidence was found that age, parity or litter size played an essential role in determining the GL. In conclusion, an unexpected high variability in gestation length in E. telfairi was demonstrated although the study animals were kept under controlled environmental conditions. The factors and mechanisms regulating this high intra-species variability in gestation length need further investigations.