The parents of 26 patients over four years of age with SCD were interviewed directly or through questionnaires to determine the incidence of enuresis and/or nocturia. Of this group, 34.6 per cent had enuresis while only 16.7 per cent of the control group registered this complaint. The incidence of hyposthenuria with enuresis and/or nocturia among these 26 patients was 69.2 per cent. Their parents and siblings also presented a high incidence of nocturia and enuresis.