The authors conducted a retrospective cohort study of unplanned care interruption (UCI) among adults initiating antiretroviral therapy (ART) from 2009 to 2011 in a Nigerian clinic. The authors used repeated measures regression to model the impact of UCI on CD4 count upon return to care and rate of CD4 change on ART. Among 2496 patients, 83% had 0, 15% had 1, and 2% had ≥2 UCIs. Mean baseline CD4 for those with 0, 1, or ≥2 UCIs was 228/cells/mm3, 355/cells/mm3, and 392/cells/mm3 ( P