RESUMEN
The diagnosis of a child's complex chronic illness may impact family relationships and cohesion. The Impact on Family Scale (IFS) is an instrument used to assess the parental perception of the effects of children's chronic illness on family life. With a sample of 110 mothers and fathers between the ages of 29 and 50 who have a child with a complex chronic illness, we examine evidence of the validity of the IFS for use in Portugal within this specific family configuration, (1) comparing its factor structure with the original one; (2) assessing its reliability; and (3) evaluating its relationship with life satisfaction and family cohesion/acceptance. As expected, CFA analysis showed that IFS is a one-factor reliable instrument with 12 items (Cronbach's alpha = 0.910), which are negatively correlated with satisfaction with life (r = -0.229, p = 0.016) and positively correlated with family acceptance and cohesion (r = 0.363; p < 0.001). The results support the validity of the IFS in families with children and adolescents with a complex chronic illness. The implications of the use of this instrument for research and professional practice is analyzed.