Background: Skin to skin care (SSC), prone (PP) and supine (SP) positions are standard positions in daily care for premature infants. Their influence on cardiorespiratory parameters and thermoregulation is discussed controversially. Objectives: We compared SSC with PP, the recommended position for preterm infants, and SP, the safest position for term infants, and tested the hypothesis that SSC has no impact on cardiorespiratory parameters and thermoregulation. Methods: In 18 spontaneously breathing premature infants [median gestational 28 weeks (24–32); chronological age 36 days (7–64), and weight 1,543 g (750–2,100)], heart and respiratory rate, breathing pattern, episodes of desaturation (<85 but ≧80 and <80%), oxygen saturation and rectal temperature were analyzed with polygraphy (Alice 3® and 3.5®) in a 6-hour measuring cycle of three subsequent series (120 min each in SP, SSC and PP) and compared (Wilcoxon test). Results: During SSC, we found no increase in apneic attacks and bradycardic episodes and no difference in respiratory rate, breathing pattern, oxygen saturation, episodes and duration of desaturation compared to SP and PP. Episodes of desaturation <85 but ≧80 and <80% were more frequent in SP compared to PP (p = 0.0421 and p = 0.0319). Heart rate increased in SSC and PP compared to SP (154.86 bpm, SD 11.55, and 153.33 bpm, SD 15.95 vs. 150.25 bpm, SD 14.64; p = 0.0013 and p = 0.0346). Temperature level was not significantly higher during SSC and PP compared to SP except a rise between the start and the end of the 6-hour measuring cycle (37.05°C, SD 0.2 vs. 37.30°C, SD 0.3; p = 0.0436). Conclusion: We found no significant SSC-mediated changes in quality and quantity of desaturations and in body temperature compared to PP in preterm infants.