Abstract The study compared up-time data gathered with automated and self-monitoring measurement systems. Six chronic low-back pain inpatients, 6 psychiatric inpatients and 6 hospital staff members were used as subjects. Concurrent recordings of up-time were taken over 4 consecutive days with the two measurement systems. Results showed that: (a) subjects across all 3 groups reported significantly less absolute up-time values from self-monitoring than automated monitoring, (b) nonpatient staff subjects exhibited greater absolute up-time levels from both measurement methods than those reported by low-back pain or psychiatric inpatients, (c) low-back pain subjects showed a greater discrepancy between absolute up-time measures from the two measurement systems than differences found for psychiatric or staff subjects, and (d) automated and self-monitoring up-time values were positively correlated within each group of subjects. It was concluded that automated and self-monitoring up-time data were not directly comparable. Expanded development and usage of automated measurement systems was recommended.