Despite the production and dissemination of recommendations related to managing fever in children, this symptom saturates the practices of primary healthcare professionals (HPs). Data on parent practices related to fever are available, but data on HPs' practices are limited. We studied HPs' practices, determinants of practices and concordance with recommendations in France. We conducted a national cross-sectional observational study between 2007 and 2008 among French general practitioners, primary care pediatricians and pharmacists. HPs were asked to include 5 consecutive patients aged 1 month to 12 years with acute fever. HPs completed a questionnaire about their practices for the current fever episode. We used a multilevel logistic regression model to assess the joint effects of patient- and HP-level variables associated with this behavior. In all, 1,534 HPs (participation rate 13%) included 6,596 children (mean age 3.7 ± 2.7 years). Physicians measured the temperature of 40% of children. Primary HPs recommended drug treatment for 84% of children (including monotherapy for 92%) and physical treatment for 62% (including all recommended physical treatments for 7%). HPs gave written advice or a pamphlet for 13% of children. Significant practice variations were associated with characteristics of the child (age, fever level and diagnosis) and HP (profession and experience). In France, despite the production and dissemination of national recommendations for managing fever in children, primary HPs' observed practices differed greatly from current recommendations, which suggests potential targets for continuing medical education.