Endoscopic retrograde brush cytology is useful for the evaluation of biliary strictures. Access across a stricture can be maintained by removing the cytology brush while leaving the sheath in the bile duct. We examined the potential for loss of diagnostic cellular material in this setting using the canine biliary system. Twenty consecutive samples were randomly collected by (1) pushing the brush from the end of the sheath or (2) pulling the brush through the length of the sheath. Slides prepared from cell suspensions were scored by a cytopathologist blinded to the collection method. Pulling the brush resulted in a significant loss of cellular material (p < 0.001). In a second phase, 23 consecutive samples were randomly obtained in the same fashion. Combining salvage cytology of material from the sheath with cytology of the pulled-brush specimens produced cellular yields similar to those of specimens obtained by pushing the brush from the sheath. If the brush is pulled from the sheath during bile duct brush cytology, we suggest that salvage cytology be performed in order to maximize the diagnostic sensitivity.