A search for pair-produced charged Higgs bosons in decays of the Z0 has been performed using the ALEPH detector at LEP for the decay channels H+H- → ντντ, H+H- → ντ cs and H+H- → cs cs. Searches for two additional decay channels in which cs is replaced by cb were also performed. With 1.17 pb-1 of integrated luminosity, corresponding to about 25 000 hadronic decays of the Z0, the charged Higgs has been excluded at 95% CL in the mass range 7.6 to 43.0 GeV for BR[H± → ντ] = 100%, 8.3 to 40.6 GeV for BR[H±→ντ] = BR[H±→cs] = 50%, and 14.4 to 35.4 GeV for BR[H±→cs] = 100% . With cs replaced by cb, the charged Higgs has been excluded at 95% CL in the mass range 12.0 to 40.7 GeV for BR[H±→ντ] = BR[H±→cb] = 50%, and 16.2 to 35.7 GeV for BR[H±→cb] = 100%. © 1990.