The present invention relates to methods for increasing homologous recombination of a nucleic acid sequence introduced into a host cell, comprising: (a) introducing into a population of filamentous fungal host cells a first nucleic acid sequence encoding a recombination protein and a second nucleic acid sequence comprising one or more regions which are homologous with the genome of the filamentous fungal host cell, wherein (i) the recombination protein promotes the recombination of the one or more regions with the corresponding homologous region in the host's genome to incorporate the second nucleic acid sequence by homologous recombination, and (ii) the number of host cells comprising the incorporated second nucleic acid sequence in the population is increased at least 20% compared to the same population without the first nucleic acid sequence; (b) and isolating from the population a filamentous fungal cell comprising the incorporated second nucleic acid sequence.