To determine the prevalence and personal and family risk factors for nocturnal enuresis (NE) among primary school children in Al-Mukalla City, Yemen, we conducted a cross-sectional survey using a self-administered, three-part structured questionnaire involving 832 school children aged 6 - 15 years between 2007 and 2008. We assessed participants' socio-demographic factors, family characteristics and factors related to the presence of NE. The mean age of the children was 11.5 (±2.7) years. The overall prevalence of NE was 28.6%, with a predominance of girls, and the prevalence decreased with increasing age (P <0.001). Factors likely to be associated with NE were pattern of sleeping (P <0.001), stressful social and psychological events (P <0.01), positive family history of enuresis (P <0.001), large family size (P >0.002) and a higher number of siblings (P = 0.01). Our findings reveal a high prevalence of NE among children in Al-Mukalla City, Yemen, with a higher prevalence in girls than in boys compared with the other studies. Sleep pattern, stressful life events, family history of NE, large family size and more children in the household may act as a risk factor for NE.