This paper contemplates the repercussions of childhood and juvenile cancer on the patients siblings. Cancer is presented as a serious illness that threatens the family s structure affecting all of its members. Since cancer is always related to death in social imagination, the family reproduces the silent conspiracy around the theme, creating obstacles to the free circulation of information about the disease and its treatment, leaving children subject to their own fantasies about the illness and treatment of their sibling. The parents, specially the mother, are frequently absent due to prolonged hospitalizations, affecting the other children who suffer important changes in their routine and are equivocally demanded to mature more rapidly. Qualitative field research was done with seven siblings, ages between 8 and 16, using semi-structured interviews whose content was analyzed in four categories: representations about illness and death; about emotions concerning the sick brother/sister; about loss and about the environment and its changes. The results point towards feelings also observed in other studies (sadness, loneliness, rejection, jealousy, rage, guilt, resentment, dissatisfaction with the information received, fear of death, feelings of loss and abandonment, complaints about the physical and emotional absence of parents, rivalry with other siblings, rupture in normality and safety in the family, changes in roles and family relationships; diminution of social life and even social isolation; scholastic difficulties; impoverishment of life’s quality; somatic complaints and preoccupation with one s own health; feelings of compassion; of maturity, of more responsibility, and of independence; increased perceptiveness and commitment; desire of more family cohesion) and also to shame, envy, altruism, heroism, and the kids expectation of having their own efforts recognized. We have interpreted and discussed the results in the light of psychoanalytic viewpoints and concluded that cancer disrupts the family with traumatic force not only due to its characteristics and association with death, but moreover, due to the sensation of helplessness and the exclusion felt by the healthy siblings. The disease and its developments bring out something incomprehensible to the child that was unprepared for the event and still was not capable of a mature reaction to the fact. This environmental failure, a flaw in the caring of the child can be lived as traumatic with short, medium and long term effects, demanding more attention and care of these siblings. However, they get neither familiar, social, scholastic or support of the health team, because these are the children no one sees.