Adult patients, \>/= 18 years of age

Patients with chronic kidney disease not on dialysis (with or without previous renal transplantation)

Treated or not with ESA at time of visit

Patients for whom the treating physician had decided to initiate Mircera for medical reasons before the commencement of the study

Initiation of treatment with Mircera at the inclusion visit

Accepting and able of completing the ESA preference questionnaire

An Observational Study of Patients' Perception of Treatment With Erythropoiesis-Stimulating Agents in Patients With Chronic Kidney Disease Not on Dialysis (PERCEPOLIS)