Determination of the exact effects of respiration rate on the heart rate variability requires comprehensive experimental studies. In this context, these two quantities should be analyzed simultaneously. In this thesis, design and implementation of a new PC-based heart rate variability recording system with respiration is described. The respiration rate is detected by a thermocouple placed in a nasal tube, whereas a single-channel electrocardiogram (ECG) signal is recorded for heart rate variability analysis in the system. The PC-based data acquisition part, which was designed in compliance to patient safety standards, has a Universal Serial Bus (USB) interface. The speed of data acquisition and patient comfort during recording make the system advantageous. The HRVs of different patients in both spontaneous and controlled breathing conditions were analyzed after short-term recordings with the system. Differences were observed in both its time-domain parameters and power spectral components.