The average birth weight of 10 132 liveborn infants delivered in the Faroes during the period 1969-81 was 3610 grams, which is the highest average weight reported by 33 countries from which we were able to obtain information. Comparison of live births only between the Faroes and Denmark shows a displacement between their birth weight curves of 225 grams. A less active elective delivery in the Faroes could not explain this considerable difference. When standardisation is made with respect to discrepancies in maternal age and marital status in the two populations, the difference between their average birth weights is increased by 5% and 9% respectively. A matching for maternal parity yields a difference between the averages which is 23% below the one between the total populations. Other factors must be responsible. Both environmental and genetic factors plus the possibility of the Faroes being closer to having an optimal birth weight than other countries are discussed.