Background In children with cerebral palsy everyday movements such as walking, standing and using one's hands can be difficult to perform because of spasticity. Botulinum neurotoxin type A (BoNT-A) are often used to reduce spasticity. The aim of this study was to describe how parents of children with cerebral palsy experienced the child's treatment with BoNT-A, how the child was affected by the treatment and how spasticity affected the child. Methods A qualitative study in which 15 parents of children (6-13 years old) with cerebral palsy were interviewed about their experiences of the BoNT-A treatment. The children had received several BoNT-A treatments. An interview guide was used with topics: the child's functions before and after the treatment, the outcomes of the treatment and how they valued the BoNT-A treatment. Content analysis was used to analyse the interviews. Results The analyses resulted in two themes: 'When softness comes and goes' and 'Both want and do not want'. The reduction of spasticity - softness - was described to promote motor functions, and facilitate the next step in motor development. The children were described as being more active out of their own initiative and having a happier mood. Spasticity, described as stiffness, was described to make walking more strenuous as well as interfering with activities. The BoNT-A injection procedure was perceived as troublesome and painful for the child, and sometimes traumatic for both children and parents. Conclusions Treatment with BoNT-A was described as facilitating motor development and activity. The children's and the parents' negative experiences of the injection procedure should be addressed.