Nucleic acid sequencing using concatemers of DNA is provided. Optionally, amplified reaction products from the repeated incorporation and excision of a nucleoside complementary to a nucleoside of the DNA to be sequenced onto primer molecules hybridized to the concatemers of DNA are detected. Nucleic acid sequencing using concatemers of DNA and non-natural oligonucleotides is also provided. Nucleic acid sequencing reactions are detected electronically and or optically using arrays of detectors.