Matthews et al 1,2 describe a high-quality genome assembly for mosquito species in a recently published Nature article. The repetitive nature of the 1.3-gigabase-long A. aegypti genome has severely hampered efforts to generate a high-quality sequence. Previous attempts resulted in patchy genomes that were assembled using short sequence reads. To overcome these challenges, Matthews et al. used next-generation sequencing to generate 166 Gb of long sequence reads with an average length of 17 kilobases. The authors used sophisticated mapping and gap-filling techniques to determine the positions of 94% of their sequence reads on the mosquito’s three chromosomes, successfully assembling 1.28 Gb of the genome. The assembly has many fewer gaps than previous assemblies, and is a 100-fold improvement in terms of its N50 — a statistical measure based on the median assembled DNA-sequence length.