Benzimidazole derivatives of formula (I): wherein: R1 is -(CH2)m-R4 or R2 is halo, -(CH2)m-NH2 or -(CH2)n-C(=NH)-NH2; R3 is H or F; R4 is -NH-(CH2)2-(NH)r-R5, -NH-(CHR5R6) or a group of the following formula (A): (A) W is -(CH2)m-, -CH2-O-CH2-, -CH2-S-CH2-, -(CH2)r-S(O)2-CH2- or -(CH2)r-NR5-CH2-; m is an integer of 1 to 3; n is 1 or 2; p is 1 and V is CH; or p is O and V is N; q is 0 or 1; r is 0 or 1; R5 is H, -S02Me, -SO2Et, -SO2CF3, -COMe, -CONMe2, - CONH2 or -CH2CH2SO2Me; R6 is H or C1-C6 alkyl; and R7 is -SO2Me, -SO2Et, -SO2CF3, -COMe, -CONMe2, - CONH2 or -CH2CH2SO2Me; and the pharmaceutically acceptable salts thereof are inhibitors of RSV and can therefore be used to treat or prevent an RSV infection.