Policies to improve access to medicines for children in low- and middle-income countries, such as Nigeria, should consider the growing threat of non-communicable diseases. The aim of this pilot study was to scope availability, price and affordability of essential cardiovascular medicines for children in selected states in Nigeria. The study was a descriptive longitudinal survey conducted in three phases. Availability was determined as percentage of facilities having the medicine on the survey date. Medicines with good availability (>80%) were noted. Prices were cross-referenced against international Reference Prices and the Nigerian National Health Insurance Scheme Prices. Affordability was calculated using the Least-Paid Government Worker method. For medicines compounded to improve availability, a model for calculating affordability was proposed. In Phase I, the availability of all 17 strengths of the cardiovascular medicines or diuretics listed in the Essential Medicines List for Children (2015) were surveyed in two conveniently selected states using the WHO/HAI questionnaire. Data were collected from 17 hospitals and pharmacies. Phases II and III focused on tablet formulations (enalapril, furosemide, hydrochlorothiazide and spironolactone) in three purposively selected state capitals: Lagos, Abuja and Yenagoa. In Phase II, 11 private pharmacies were surveyed in December 2016: Phase III tracked price changes in Abuja and Yenagoa in August 2018. Only furosemide and hydrochlorothiazide tablets had good availability. Oral liquids were unavailable. Prices for four generic oral tablets were 2-16× higher than the International Reference Prices; prices for two of these did not change significantly over the study period. Affordable medicines were generic furosemide and hydrochlorothiazide tablet. Where a fee is charged, compounded medicines were also not affordable. While the small sample sizes limit generalization, this study provides indicative data suggesting that prices for cardiovascular medicines remain high and potentially unaffordable in the private sector in these selected states, and when compounded. Regular systematic access surveys are needed.