Because of the growing demand to evaluate cardiorespiratory dysfunctions the short-time oxycardiorespirography becomes a more and more important and powerful tool in the daily clinical routine. Therefore, from about one hour lasting records we studied the distribution of MA-values (mean apnea duration), duration of the longest apnea, percentage of periodic breathing time, lowest heart rate values, lowest transcutaneous PO2 values and highest transcutaneous PCO2 values in an obstetrical optimal low-risk group of 90 infants and a obstetrical non-optimal group of 152 infants between four and ten weeks of age. Percentiles of each variable were calculated, and we suggest the 90th percentiles as new threshold values to judge these short-time recordings. In comparison to relevant data from the literature we could demonstrate that deviating threshold values have to be applied to short-time recordings in comparison to long-time recordings. In addition, the respiratory behaviour of the optimal group is compared to that of the non-optimal group of the same age. Interestingly enough, no difference in the respiratory behaviour between these groups could be demonstrated.