Living with a childhood chronic disease can be challenging, especially if the diagnosis involves a rare condition. This study sought to elucidate how the diagnosis of a rare disease, as compared to a common, chronic condition, may influence maternal experiences of childhood illness. We conducted face-to-face, semi-structured interviews with 26 mothers of children treated in a pediatric hospital in the province of Lecco, Italy. Half of the participants had a child diagnosed with Bartter syndrome (BS), and the rest had a child suffering from celiac disease (CD). Interviews were recorded, transcribed, and analyzed using an inductive thematic approach. We identified three main themes from the analysis of our data: (1) disrupted normality and the need to know, (2) reconstructing normality, and (3) acting “normal.” Although most participants experienced the disclosure of diagnosis as a relief, processes that facilitated normality reconstruction in celiac families, notably access to appropriate information, social support, and personal contact with comparison others, were found to be important stressors for mothers living with BS.Conclusion: This comparative qualitative study provides evidence on how well-known problems associated with the rarity of childhood diseases impact on families’ efforts to cope with the illness and regain a sense of normality. What is Known: • Families living with a rare disease have been found to experience a range of common problems, directly linked to the rarity of these pathologies. What is New: • Maximization of both emotional and instrumental social support, through provision of appropriate information or establishment of disease-specific support groups, could greatly contribute to rare disease families’ efforts to cope with childhood illness and regain a sense of normality. Electronic supplementary materialThe online version of this article (10.1007/s00431-017-3085-7) contains supplementary material, which is available to authorized users.