['Profiles of allergic sensitization are poorly documented in infancy. Relations between early sensitization and allergic morbidity need to be clarified.', 'This study dealt with children involved in the Pollution and Asthma Risk: an Infant Study (PARIS), a population-based prospective birth cohort. Allergic sensitization to twelve food and four inhalant allergens was assessed at 18\xa0months and defined by a specific immunoglobulin E (IgE) level ≥0.35\xa0kU', 'Sensitization to any allergen concerned 13.6% of infants. By cluster analysis, 1525 infants were grouped into three profiles: 89.2% not or rarely sensitized (only 3.7% of sensitized), 9.2% mainly sensitized to one or few allergens (45.2% of monosensitized and 45.9% of paucisensitized) and 1.6% all polysensitized. The prevalence of doctor-diagnosed asthma, rhinitis, eczema, food allergy and multimorbidity at 2\xa0years increased from profile one to profile three (p-trend <0.001). At 6\xa0years, symptoms of current asthma, rhinitis, eczema and multimorbidity were significantly more frequent in the last two profiles.'] Is early polysensitization associated with allergic multimorbidity in PARIS birth cohort infants?