The aim of this study was to identify the factors of variation of rumen temperatures in goats and to estimate the genetic parameters of that trait. 97 Alpine goats from an INRAE experimental farm were monitored continuously during their first lactation (267 days on average, from kidding to dry off) using Medria rumen temperature boluses (ThermoBolus San’Phone®). Temperatures were collected every 5 min (288 records per day) and have been corrected to account for drinking events. The average rumen temperature was 39.68 ± 0.51°C on the whole data set (n=7,273,000). The average temperature during the day increased from about 5.00AM to about 5.00PM and decreased afterwards: the minimum temperatures (39.28°C) were observed in early morning (between 5.00AM and 5.30AM) whereas the maximum temperatures were observed in late afternoon (39.94°C between 4.30PM and 5.00PM). In addition to the time, the phenotypic variability was also explained by the date, the birth year, the stage of lactation and the milk yield of the goat. Genetic parameters were estimated using a linear repeatability model. Data were spread into 5 periods according to their raw mean temperature and standard deviation (4.30AM-6.00AM, 6.40AM-1.20PM, 3.30PM-8.00PM, 9.00PM-3.00AM) and each one was analysed separately. Repeatability varied from 0.20 (4.30AM-6.00AM) to 0.32 (3.30PM-8.00PM), and heritability from 0.03 (4.30AM-6.00AM) to 0.12 (9.00PM-3.00AM). For this last period, breeding values ranged from -0.10 to +0.14 °C. These results suggest that body temperature measured by internal sensors has a genetic control, which is potentially linked to basal metabolism or response to various stressors (heat stress, infection). This study has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 772787 (SMARTER)