450 cardio-pneumograms (CPG) were performed on two successive nights in 68 controls and 235 SIDS siblings. The number of respiratory pauses greater than or equal to 5 sec and greater than or equal to 10 sec (NP) and the time of periodic breathing (PB) were calculated per 100 minutes of recording. Recordings were arranged into five age groups corresponding to the 1st, 2nd, 3rd, 4th and 5th-6th month of life. No significant differences in NP and PB were found when controls and SIDS siblings were compared separately within each age group, neither as a function of gestational age (less than 40 weeks GA vs greater than or equal to 40 weeks GA), nor as a function of the results of the 1st vs the 2nd night of recording. Nor was any significant difference in NP and PB found when comparing control vs sibling babies within each age group for the 1st or for the 2nd night of recording. In SIDS siblings, there was a significant decrease in the three variables studied between the 1st and the 2nd month of life. No significant decrease was found in controls. We conclude that SIDS siblings are not different from controls of the same age when respiratory variables are studied by CPG recordings.