PURPOSETo describe experiences of fear, coping, and support in 10-17-year-old children under treatment for acute lymphoblastic leukaemia (ALL).METHODSA longitudinal descriptive qualitative design was adopted. Ten children participated in one to three interviews each (24 interviews in all). Interviews were analysed using a matrix-based qualitative method.RESULTSThe variety of fears described related to uncertainty, pain and medical procedures, bodily changes and loss of control, complications, professionals' attitudes, affected school results, and social isolation. Children used various strategies to deal with fear: some more general, to cope with the whole situation, and others more related to specific events such as treatment and tests. The most reported strategies we labelled Accepting the situation, Positive thinking, and Being an active agent. Less favourable strategies were also reported. Health care professionals, families, and friends offered valuable, but different kinds of, support.CONCLUSIONSChildren aged 10 to 17 undergoing treatment for ALL experience various fears. Each experience is individual and changes over time, but there are common patterns. Most children used problem-solving or emotional-regulation strategies, but withdrawal was also reported. Even children who can deal with fear need support from their health care professionals, families, and friends.