Suction rectal biopsy (SRB) may not include sufficient submucosa for histological diagnosis of Hirschsprung's disease (HD) and a repeat biopsy is required. Substitution of the conventional syringe for sustained suction from a machine or wall suction unit could provide a more consistently adequate tissue biopsy. This study was conducted to compare the adequacy of SRB specimens using a conventional method of syringe suction (SSRB) with those taken by wall or machine suction (WSRB). Hospital records of patients who had a SRB between 2002 and 2004 were studied retrospectively. The biopsy was considered inadequate if there was insufficient submucosa and a repeat specimen was requested. SSRB were taken using the conventional SSRB technique. WSRB were taken with the same Noblett forceps but with suction from wall suction or from a portable suction machine. Ninety-five infants had 103 SRB, 24 had WSRB and all (100%) were adequate for histopathological diagnosis or exclusion of HD. Seventy nine conventional SSRB were undertaken in 71 infants of which 64 (81.02%) were adequate. The difference in adequacy between WSRB and SSRB was statistically significant (P = 0.02). There were no instances of haemorrhage or bowel perforation in either subgroup. WSRB with the Noblett biopsy forceps is more likely to produce an adequate specimen and to reduce the incidence of repeat biopsies.