Long oligonucleotide arrays, as well as methods for their preparation and use in hybridization assays, are provided. The subject arrays are characterized in that at least a portion of the probes of the array, and usually all of the probes of the array, are long oligonucleotides, e.g. oligonucleotides having a length of from about 50 to 120 nt. Each long oligonucleotide probe on the array is preferably chosen to exhibit substantially the same high target binding efficiency and substantially the same low non-specific binding under conditions in which the array is employed. The subject arrays find use in a number of different applications, e.g. differential gene expression analysis.