-A field experiment was conducted in Santa Helena de Goiás to evaluate the selectivity of herbicides fomesafen and clomazone and other combinations to cotton plants when applied in preemergence. The experiment was conducted in a randomized block design in a split plot design with four replications. The assessed herbicide treatments were: clomazone, clomazone + fomesafen (0.45 kg ha -1 of a.i.), clomazone + fomesafen (0.625 kg ha -1 of a.i.), clomazone + fomesafen + diuron, clomazone + fomesafen + prometryn, clomazone + fomesafen + trifluralin and clomazone + fomesafen + s-metolachlor. The visual symptoms of phytotoxicity were seen up to the evaluation of 19 days after emergence, and generally the injuries were higher where it was associated with three herbicides in the application. The treatments with clomazone alone and the associations clomazone + fomesafen (1.0 + 0.45 kg ha -1 of a.i.), clomazone + fomesafen + diuron, clomazone + fomesafen + prometryn, clomazone + fomesafen + trifluralin and clomazone + fomesafen + smetolachlor were selective to cotton plant. The highest dose of fomesafen (0.625 kg ha -1 of a.i.) in associations with clomazone (1.0 kg ha -1 of a.i.) was not selective to cotton plant (cultivar DP 555 BG RR and in a clayey textured soil, with 3.1% of OM and pH of 6.0). Keywords: chemical control; Gossypium hirsutum r. Latifolia; tank mix Resumo -Um experimento de campo foi realizado em Santa Helena de Goiás para avaliar a seletividade dos herbicidas fomesafen e clomazone e outras associações ao algodoeiro, quando aplicados em pré-emergência. O experimento foi conduzido em delineamento de blocos casualizados em esquema de parcelas subdivididas, com quatro repetições. Os tratamentos herbicidas avaliados foram: clomazone, clomazone + fomesafen (0,45 kg ha -1 de i.a.), clomazone + fomesafen (0,625 kg ha -1 de i.a.), clomazone + fomesafen + diuron, clomazone + fomesafen + prometryn, clomazone + fomesafen + trifluralin e clomazone + fomesafen + s-metolachlor. Os sintomas visuais de fitointoxicação foram visualizados até a avaliação de 19 dias após a emergência, e de modo geral, as injúrias foram maiores onde foi associado três herbicidas na aplicação. Os tratamentos com clomazone isolado e as associações clomazone + fomesafen (1,0 + 1 Received for publication on 20/08/2015 and approved on 14/10/2015.