We assessed the prevalence of underweight, wasting and stunting among preschool children in Oman from March to December 1999. Within each region, samples of males and females in the age groups 0-5, 6-11, 12-23, 24-35, 36-47 and 48-60 months were drawn from the registers of health institutions and the weight and height/length of the children were measured. The total sample comprised 19 440 children; 9911 males and 9529 females. Data were analysed according to the World Health Organization protocols. The prevalence rates of wasting, stunting and underweight were 7.0%, 10.6% and 17.9% respectively at the national level. There were no sex differences.