PURPOSE: This study was done to explore the meaning of joys and sorrows in mothers of children with Mucopolysaccharidosis (MPS). METHODS: The participants were 9 mothers who each had a child with MPS. Data were gathered using in-depth interviews. The interviews were recorded and transcribed verbatim. Data were analyzed using Colaizzi method. RESULTS: The significant results from analyzing the interviews can be grouped into 12 concept descriptions, and 5 theme clusters. The essential theme clusters for the experience of the mothers were 'hopelessness about this rare disease', 'guilt because of the disease being hereditary', 'endless courses of treatment', 'wounds in the relationship', and 'relative composure of mind'. CONCLUSION: The finding of this study offer profound information on joys and sorrows experienced by mothers of children with MPS and provide basic data for developing nursing intervention strategies for the mothers of children with rare diseases.