Objective: To determine the number and distribution of paediatricians in Nigeria. It also aims to determine the association between paediatrician workforce and under five mortality (U5MR) and immunization coverageacross the six geopolitical zones of the country.Methods: The part II fellowship examination pass list of the West African College of Physicians and the National Postgraduate Medical College and the register and financial records of the Paediatric Association of Nigeria were searched for the purpose of the study. Using a structured questionnaire, personal and professional data was obtained frommembers at the 2011 Annual Paediatric Association of Nigeria Conference or via the Association’s website, email network and phone calls to Departments of Paediatrics in institutions (private and public) across the Country. Data on the paediatricians residing within Nigeria was then extracted from the comprehensive database and subsequently analyzed.Population data, mortality and immunization rates were obtained from the National Population Commission census and their most recent National Demographic health survey in Nigeria. Correlations were drawn betweennumber of paediatricians and U5MR and diphtheria-pertussistetanus(DPT) vaccine coverage.Results: There were 492 practicing paediatricians in Nigeria at theend of year 2011, comprising 282 (57.3%) males and 210 (42.7%)females; 476 (96.7%). Majority (84.7%) worked for the governmentwith 97% of them in hospital settings, mostly tertiary centres (344=88%). Lagos State had the highest number (85; 17.9%) of practicing paediatricians followed by the Federal Capital Territory with 37 (7.8%) paediatricians. More than two thirds of the paediatricians (336; 70.6%) were practicing in the southern part of the country. The average child:p a e d i a t r i c i a n r a t i o wa s 157,878:1for the country. TheNorth East zone had the highest chi ld- to-pa ediat r ician rat io (718,412:1) while South West had the lowest ratio (95,682:1).Higher absolute numbers of paediatricians in each zone were associatedwi th lower U5MR (Spearman ñ=-0.94, p=0.0048), accounting for 84% of the variability among zones. Higher ratios of child-to-paediatrician were significantly associated with higher U5MR (Spearman ñ=0.82, p=0.04,linear R2=0.73) and marginally with lower DPT coverage by geopoliticalzone (Spearman ñ=-0.77, p=0.07, linear R2=0.59).Conclusion: The study reveals that the number of paediatricians inNigeria is grossly inadequate with a huge child-to-paediatrician ratio.There is also an uneven distribution of the paediatricians with higher numbers in the southern states. Zones of the country with lower child-to-paediatrician ratios also experienced lower U5MR. There is a need to train more paediatricians in Nigeria and promote an even distribution of the paediatrician workforceKey words: Paediatrician, workforce, child-to-paediatrician ratio, under-5 mortality, immunization, childhealth, Nigeria