PURPOSE: This qualitative study aimed to identify the common, lived experiences of grandmothers who cared for their grandchildren as the primary caregivers. METHODS: This study was based on the phenomenological method described by Colaizzi (1978). RESULTS: Seven theme clusters emerged from the data as follows: "grandmother caregivers accept the parenting role of the incessant responsibilities and the distrust of non-kin caregivers.", "grandmother caregivers have a double maternal roles; an instrument-oriented maternal role to their own child and relationship-oriented maternal role to their grandchild.", "grandmother caregivers are partially authorized to make decisions in the matters of their grandchild.", "grandmother caregivers suffer a deterioration in their health by an acceleration of the aging process.", "caregiving causes grandmother caregivers to feel a sense of social isolation, and persue various coping strategies to control this feeling.", "grandmother caregivers have a greater feeling of self-esteem, but they often conflict with their adult children if they don't feel appreciated by them.", "grandmother caregivers have limited social support and their health issues are often overlooked in the family context." CONCLUSION: The results of this study can guide nurses and health care workers to understand the experiences of grandmother caregivers and to implement individualized nursing interventions suited for them.