Objective To investigate the relationship of attentional orientation,sensory disorder or magnitude estimation with cross-over effect in the line bisection of hemispatial neglect patients and to evaluate the influences of the length of lines and cueing on the performance of line bisection of neglect patients.Methods Fifteen patients with hemispatial neglect and 15 age and education-level-matched healthy controls underwent line bisection experiment.in which difierent types of cues and difierent length of bisected lines were given to observe their effects on the deviation.Analyses of variance (ANOVAs)were used to analyze the data in each group.Results When the lengths of lines were 4,6,8,10,12 cm,percentages of line bisection deviation(%)without cue were-5.71±5.13,-2.48±8.83,-1.18±10.90.0.43±8.12,2.17±7.04 respectively.The experiment showed that deviation was related to the length of lines ( F=12.5,P＜0.01).Nine patients exhibited cross-over effect when the lines were shorter than 10 cm.Another interesting result was that ipsilesional cues led to a reduction in bisection errors ( percentages of line bisection deviation(%)were-3.93±7.04,2.43±6.34,4.93±5.19,6.49±3.36,6.38±4.18,P＜0.01),however,contralesional ones resulted in a reverse effect(percentages of bisection deviation(%)were-10.93±8.85,-7.95±8.44,-4.14±8.37,-2.60±9.96,-1.57±10.67,P=0.03).As for bilateral cues,both cueing had no influence on line bisection(percentages of bisection deviation(%)were -5.93±7.76,-0.52±8.20,0.54±6.34.2.57±5.02,2.79±3.92,P=0.35).The length of cues had no influence on line bisection(F=1.94.P=0.1 4).Condusions The subjective midpoint excurses toward left when the length of line is relatively short.which is referred as crossover effect.indicating magnitude estimation a factor of crossover effect.Unilateral cues affects the performance of line dissection of neglect patients.which may be accounted for attentional orientational biases.No effect of the cue length suggested sensory disorder does not play a role in the crossover effect.